bluuebunny/crossref_metadata_2025 huggingface dataset:
Is carbohydrate-deficient transferrin in serum useful for detecting excessive alcohol consumption in hypertensive patients?
Authors: Fagerberg B , Agewall S , Berglund A , Wysocki M , Lundberg P A , Lindstedt G
Published: January 2020

The aim of this study was to examine the diagnostic usefulness of carbohydrate-deficient transferrin (CDT) in serum in a cross-sectional study of 439 treated hypertensive men. We related the results to alcohol intake by questionnaire and to biochemical and hemodynamic measurements known to reflect excessive alcohol consumption. The diagnostic sensitivity and the specificity for high alcohol intake (> or = 24 g/day of ethanol) were 44% and 87%, respectively. The group with reported high alcohol intake (n = 32) was characterized by hemodynamic and biochemical changes typical of alcohol abuse. The corresponding profile for the patients with increased serum CDT concentrations (n = 70) was different in several respects, indicating a considerable number of false-positive tests. We conclude that serum CDT determination had low sensitivity and specificity for excessive alcohol consumption in this group of hypertensive patients. The results illustrate the importance of evaluating new laboratory methods in unselected patient populations before drawing any conclusions about their clinical value.
Creatine kinase isoenzyme BB increased in serum and tumor tissue of patients with giant cell tumor of bone
Authors: Fukuda J , Yagishita S , Yamaoka K , Hanihara T , Kushida K , Murayama H
Published: January 2020

Increased creatine kinase isoenzyme BB (CK-BB) has been observed in sera from patients with brain injuries and occasionally in sera from patients with malignancy. We report here that, in two patients with giant cell tumor of bone (GCT), preoperative serum CK-BB increased to approximately 20 and 90 U/L, but in postoperative serum the CK-BB decreased to normal values. That the tumors contained CK-BB was indicated by electrophoretic analysis and immunohistochemical staining. Furthermore, serum CK-BB was detectable in five additional cases of GCT and in cultured tumor cells from a patient with GCT by an electrophoretic method. These results suggest that CK-BB may be a marker for GCT.
Use of cardiac troponin I to diagnose perioperative myocardial infarction in coronary artery bypass grafting
Authors: Mair J , Larue C , Mair P , Balogh D , Calzolari C , Puschendorf B
Published: January 2020

Cardiac troponin I (cTnI) is a regulatory protein unique to myocardium. We used a cardiospecific 30-min ELISA to measure cTnI in EDTA-plasma samples serially drawn from 28 patients before and after coronary artery bypass grafting (CABG)--26 elective and 2 salvage cases. The cTnI increase in 22 of the elective CABG patients, who did not have perioperative myocardial infarction (not-PMI), reflected the inevitable myocardial damage caused by cannulation and cardioplegic arrest, with peak values of 1.7 +/- 1.0 microgram/L (mean + 2 SD = 3.7 micrograms/L), the peaks occurring on average 8 h (range 4-24) after aortic unclamping. Two of the 22 not-PMI, elective CABG patients showed cTnI peaks > 3.0 micrograms/L (3.9 and 3.4 micrograms/L), indicating more extensive perioperative myocardial damage than the other 20, as confirmed by clinical and electrocardiographic or echocardiographic signs, although creatine kinase isoenzyme MB (CKMB) activity was below our PMI decision limit of 20 U/L (25 degrees C). As classified by electrocardiography, echocardiography, and increased CKMB activity, four of the 26 elective CABG patients did have a PMI. One patient with Q-wave PMI had peak cTnI approximately 30 micrograms/L, and three with non-Q-wave PMI had lower peak values (approximately 5 micrograms/L). The two salvage CABG cases had increased cTnI before surgery. One developed a Q-wave acute myocardial infarction with a 3-h cTnI peak of approximately 35 micrograms/L. We conclude that, after elective CABG, cTnI peaks > 3.7 micrograms/L and concentrations > 3.1 micrograms/L at 12 h or 2.5 micrograms/L at 24 h indicate PMI with high probability.
Hormone conference at Sahlgren's University Hospital: polycythemia and inappropriately high serum erythropoietin concentration in a 62-year-old man
Authors: Lindstedt G , Lundberg P A , Norrby A , Kutti J , Andersen O , Jakobsson K E , Nordborg C , Bengtsson B A
Published: January 2020

A 62-year-old man with a history of coronary insufficiency complained at his scheduled visit to the outpatient clinic of symptoms suggestive of gastritis. His blood hemoglobin concentration, however, was markedly increased. Results of a hematological work-up suggested an erythropoietin-producing tumor. Signs of increased intracranial pressure then led to the finding of a cerebellar tumor, which could explain his vertigo and abdominal symptoms. This cystic capillary hemangioblastoma probably was responsible for the erythropoietin production and also seemed to produce basic fibroblast growth factor. The clinical evaluation of polycythemia as well as erythropoietin biochemistry and clinical application are reviewed.
Autoimmune endocrinopathies: aspects of pathogenesis and the role of immune assays in investigation and management
Authors: Volpé R
Published: January 2020

It has been hypothesized over many years that the autoimmune endocrine diseases are each due to antigen-specific defects in suppressor (regulatory) T lymphocyte function. There is now increasing evidence in studies of autoimmune thyroid disease and insulin-dependent diabetes mellitus that suppressor cells are activated by irrelevant antigens but respond inadequately to specific relevant antigens. These inadequate responses are insufficient in themselves to precipitate the autoimmune disease; further insults from the environment increase the deficiencies in regulatory cell activity, adding to the genetically induced dysfunction, i.e., specific defects in antigen presentation. Diagnostic procedures for autoimmune endocrine diseases include tests of target cell function and the detection of various antibodies, which are becoming increasingly useful in prediction, diagnosis, and management of these diseases.
Laboratory diagnosis and monitoring in chronic systemic autoimmune diseases
Authors: Osterland C K
Published: January 2020

The testing done in the diagnostic immunology laboratory contributes to the management of patients with systemic autoimmune diseases. In these diseases the interaction between environmental factors and a genetically dysregulated immune system produces a continually variable level of disease activity. Improved techniques now allow the clinical scientist to assess the integrity of a patient's immune system and to ascertain qualitative or quantitative disturbances in its activation and expression. Cellular and humoral immunity may become independently activated or dysfunctional in certain disease processes, although the generation of amplifying proteins may result in the full clinical expression of immunity and autoimmune inflammation. Autoimmune diseases can, in part, be characterized according to the activation pattern of gene expression encoding the amplifying and proinflammatory cytokines. Modern therapy is increasingly aimed at determining ways to influence discrete elements of the immune apparatus; therefore, it is important to identify and characterize the patterns of expression of the immune system mediators serially in chronic autoimmune disease states. Newer diagnostic procedures stemming from observations in basic and clinical research are expanding the useful database on patients, but they must be carefully evaluated to prove their applicability and efficacy. Because blood samples are the best available specimens for testing, one must consider all the possible sampling problems and pitfalls of using results from peripheral blood to judge changes in function of the lymphoid system.
The monoclonal gammopathies
Authors: Kyle R A
Published: January 2020

Each monoclonal protein (M-protein, or myeloma protein) consists of two heavy polypeptide chains of the same class and subclass and two light polypeptide chains of the same type. Electrophoresis on cellulose acetate membranes is satisfactory for screening, although agarose electrophoresis is more sensitive for detecting small M-proteins. Immunoelectrophoresis should be performed when myeloma, macroglobulinemia, amyloidosis, or a related disorder is suspected. Immunofixation is useful when results of immunoelectrophoresis are equivocal. The recognition of a Bence Jones protein depends on the demonstration of a monoclonal light chain by immunoelectrophoresis or immunofixation of an adequately concentrated urine specimen. The differential diagnosis of an M-protein includes monoclonal gammopathy of undetermined significance (benign monoclonal gammopathy), multiple myeloma, solitary plasmacytoma of bone or extramedullary plasmacytoma, macroglobulinemia, lymphoma, chronic lymphocytic leukemia, and primary systemic amyloidosis.
Metabolic determinants of the course of coronary artery disease in men
Authors: Watts G F , Mandalia S , Slavin B M , Brunt J N , Coltart D J , Lewis B
Published: January 2020

We examined associations between metabolic variables and changes in coronary artery disease (CAD) in the St. Thomas' Atherosclerosis Regression Study (STARS). The course of CAD over 3 years was measured continually by quantitative coronary angiography, i.e., as the per patient change in the mean absolute width of coronary segments (delta MAWS). The decrease in MAWS (progression of CAD) was significantly correlated with in-trial plasma concentrations of cholesterol (P = 0.002), low-density lipoprotein (LDL) cholesterol (P = 0.001), apolipoprotein B (apoB) (P = 0.008), and lipoprotein(a) [Lp(a)] (P = 0.004); no significant associations were found with high-density lipoprotein (HDL) cholesterol, apoA-I, vitamin E, thyroid hormones, fibrinogen, von Willebrand factor, or post-load plasma glucose and insulin concentrations. By multiple regression analysis, LDL cholesterol was the best predictor of delta MAWS, the adjusted model explaining 22% of the variance (P = 0.04). Thus, in men with symptomatic CAD the most important metabolic predictor of change in CAD is plasma LDL cholesterol, there being no advantage in measuring other variables, in particular, apoB or Lp(a).
Quantification of hemoglobin variants by capillary isoelectric focusing
Authors: Hempe J M , Craver R D
Published: January 2020

Capillary isoelectric focusing (cIEF) was used to identify and quantify major and minor hemoglobin (Hb) variants. Whole blood (approximately 10 microL required) hemolysate was analyzed with a commercial instrument equipped with a 50 microns (i.d.) x 27 cm coated capillary filled with 20 g/L ampholytes (pH 6-8) in 4 g/L methylcellulose (MC). Cathode and anode solutions were 20 mol/L NaOH and 100 mol/L H3PO4 in MC, respectively. Samples (approximately 40 nL) were applied via autosampler by low-pressure injection, focused for 3 min at 30 kV, and mobilized by simultaneous voltage and low pressure past the detector, where absorbance at 415 nm was analyzed by an automated data acquisition system. Blood from subjects with sickle cell trait, Hb S/C disease, and various beta-thalassemias were analyzed by cIEF in < 15 min. cIEF was used to separate Hb S from Hb D-Los Angeles. Assay precision determined with commercial controls gave CV < 2% for Hb A and S, and 1-11% for minor Hb variants A2, F, and A1c. Results obtained by cIEF for patients' samples agreed well with values determined by conventional assays (r2 > 0.95). The results demonstrate that cIEF is a rapid, sensitive, high-resolution automated method for routine quantitative clinical analysis of Hb variants.
Is determination of creatine kinase-2 after electrophoretic separation accurate?
Authors: Henderson A R , Stark J A , McQueen M J , Patten R L , Krishnan S , Wood D E , Webb S
Published: January 2020

Since 1991, the Ontario Laboratory Proficiency Testing Program has assessed the analytical performance of creatine kinase (CK; EC 2.7.3.2) isoenzyme-2, using fresh human serum supplemented with purified human CK isoenzymes. In Ontario, the 142 laboratories licensed to analyze CK-2 use a variety of methods: electrophoresis-based, immunoinhibition, and mass assays. During a 1992 survey, duplicate CK-2 samples with different total CK activities showed poorer precision when analyzed after electrophoretic separation than by any other method. A 1993 survey designed to validate these observations conclusively showed that electrophoresis-based assays are subject to a bias proportional to the total CK activity. These survey results were confirmed by studies with selected patients' specimens. We therefore conclude that electrophoresis-based assays may not warrant their reputation as the gold standard for CK isoenzyme measurement.
Characterization of drug interferences caused by coelution of substances in gas chromatography/mass spectrometry confirmation of targeted drugs in full-scan and selected-ion monitoring modes
Authors: Wu A H , Ostheimer D , Cremese M , Forte E , Hill D
Published: January 2020

Interference by substances coeluting with targeted drugs is a general problem for gas chromatographic/mass spectrometric analysis of urine. To characterize these interferences, we examined human urine samples containing benzoylecgonine and fluconazole, and other drug combinations including deuterated internal standards that coelute (ISd,c) with target drugs, by selected-ion monitoring (SIM) and full-scan mass spectrometry. We show that, by SIM analysis, detecting the presence of an interferent is dependent on the specific IS used for the assay. When an ISd,c is used, the presence of another coeluting substance (interferent) suggests that the intensity of IS ions is substantially diminished, because the interferent affects both the ISd,c and target drug. When a noncoeluting IS (ISnc) is used, the interferent cannot be discerned unless it coincidently contains one or more of the ions monitored for either the target drug or ISnc. Under full-scan analysis, a coeluting interferent is directly discernable by examining the total ion gas chromatogram.
One-hour test for estimating intestinal absorption of calcium by using stable strontium as a marker
Authors: Sips A J , Netelenbos J C , Barto R , Lips P , van der Vijgh W J
Published: January 2020

Intestinal absorption of calcium is a relevant marker in a broad spectrum of diseases; however, its determination in clinical practice is difficult. Our aim was to design a simple test for this based on stable strontium (88Sr). The correlation between the intestinal absorption of simultaneously administered 45Ca and 88Sr was investigated in patients with various disorders of the bone and calcium metabolism. The area under the curve for the period 0-60 min after dosing (AUC0-60 in mmol.L-1.min), being a representative measure of intestinal absorption, showed a close correlation between both elements (r = 0.90, P < 0.001). Moreover, the measure of agreement in classifying the patients as low, intermediate, or high absorbers was high (kappa = 0.80). We conclude that a test based on measuring AUC0-60 of strontium is a fast and inexpensive way to obtain reliable information about the level of intestinal calcium absorption.
Overview of mood disorders: diagnosis, classification, and management
Authors: Fawcett J
Published: January 2020

This discussion of the diagnosis, classification, and epidemiology of clinical depression includes details of the associated physical morbidity, mortality, and impairment. Treatment approaches to depressive disorders are categorized with an emphasis on medication management, including improved treatment efficacy and progress with respect to side effects and toxicity. Although considerable advances have been made, with 18 antidepressant compounds being available and the impending release of two new antidepressant compounds in 1994, no one agent has demonstrated greater efficacy than another. Currently available studies suggest that only 21-42% of patients entered into treatment reach full recovery, while 20% of patients do not respond to available treatment but remain chronically depressed. Thus, the development of more efficacious agents that will produce complete remissions in patients who now achieve only partial treatment responses is a major challenge for biochemical, pharmacological, and clinical research of the treatment of mood disorders.
Lithium and the brain: a psychopharmacological strategy to a molecular basis for manic depressive illness
Authors: Lenox R H , Watson D G
Published: January 2020

Lithium, an effective treatment for mania and the prevention of recurrent episodes of both mania and depression in patients with manic depressive illness, exerts multiple biochemical effects. However, any clinically relevant site of action of lithium must occur at therapeutic concentrations attained in the brain of patients and must account for the lag period accompanying onset of action as well as effects persisting beyond discontinuation of treatment. This monovalent cation acts as a potent uncompetitive inhibitor in the receptor-coupled breakdown of inositol phospholipids, resulting in a relative depletion of inositol and an alteration in the generation of diacylglycerol, an endogenous activator of protein kinase C. In our laboratory, we are examining the action of chronically administered lithium on posttranslational modification of specific phosphoproteins involved in regulating signal transduction in the brain. We have found that chronic, but not acute, administration of lithium in rats markedly reduces a major phosphoprotein substrate of protein kinase C in the hippocampus, an effect that persists beyond the cessation of lithium treatment. This protein, myristoylated alanine-rich C kinase substrate ("MARCKS"), is implicated in synaptic neurotransmission, calcium regulation, and cytoskeletal restructuring. These findings have relevance for the long-term action of lithium in stabilizing an underlying dysregulation in the brain and may move us closer to formulating a molecular basis of manic depressive illness.
Two methods for measuring carbohydrate-deficient transferrin in inpatient alcoholics and healthy controls compared
Authors: Anton R , Bean P
Published: January 2020

Carbohydrate-deficient transferrins (CDTs), naturally occurring glycosylated transferrin proteins, are reported to be increased in the serum of individuals who consume large quantities of alcohol (ethanol). We compared two methods for the separation and quantification of CDT, using the same alcohol-dependent patients and age-, gender-, and race-matched controls as sources of samples for both assays. There was good correlation (r = 0.89) between the microcolumn anion-exchange chromatography/RIA (MAEC/RIA) procedure and the isoelectric focusing, immunoblotting, and laser densitometry (IEF/IB/LD) procedure. Receiver operating characteristic analysis suggested that the IEF/IB/LD procedure would perform slightly better than MAEC/RIA for the overall population. However, both assays were much more sensitive for the detection of heavy alcohol consumption in men, compared with women. Alcohol consumption in the week prior to CDT measurement correlated only weakly with the concentrations measured with either assay.
Nonlinearity of high-density lipoprotein cholesterol determinations is matrix dependent
Authors: Kroll M H , Chesler R
Published: January 2020

The majority of methods for determining high-density lipoprotein (HDL) cholesterol failed the 1991 College of American Pathologists (CAP) linearity survey (sets LN2-A, B, C). We hypothesized that they failed because of the survey material matrix. We evaluated linearity with dextran sulfate or phosphotungstate as the precipitating reagents for several methods: Ektachem; TDx; Sigma; Dimension; Cobas Fara, with Roche reagents; and the Hitachi 736, with precipitating reagents from Boehringer Mannheim Diagnostics. We tested CAP survey material, Sigma HDL-cholesterol control material, and a fresh serum pool for linearity, using the polynomial method. All of the methods were nonlinear for the CAP material and for the controls precipitated after dilution. Five of eight methods were linear for the control materials precipitated before dilution. All methods but one were linear for the serum pool. These results demonstrate that the source of the nonlinearity is located in the precipitation step and depends on the sample matrix.
Evaluation of Ciba Corning ACS:180 automated immunoassay system
Authors: Mora-Brugués J , Gascón-Roche N , Rodríguez-Espinosa J , Cortés-Rius M , González-Sastre F
Published: January 2020

We evaluated the technical performance of the Ciba Corning ACS:180 automated immunoassay system for the following analytes: thyroid-stimulating hormone, free thyroxine, luteinizing hormone, follicle-stimulating hormone, prolactin, human chorionic gonadotropin, carcino-embryonic antigen, and prostate-specific antigen. The characteristics evaluated were: precision, carryover, linearity, lower limit of detection, analytical interferences, and comparison with other methods. Satisfactory results were obtained in the within-run and between-run precision studies. Neither sample nor reagent carryover was found for any assay. The range of linearity was acceptable. For some of the assays evaluated, the lower limit of detection was better than that claimed by the manufacturer. Correlation between ACS:180 methods and compared methods was adequate. We conclude that the ACS:180 offers good reliability, practicability, and performance capabilities.
Interference of ofloxacin with determination of urinary porphyrins
Authors: Schoenfeld N , Mamet R
Published: January 2020

The second-generation quinolone ofloxacin interferes with the screening test of porphyrins. We observed a 20-fold increase in the porphyrin concentration measured in urine of an ofloxacin-treated patient, compared with drug-free normal urine. Two other fluorinated 4-quinolones tested, norfloxacin and ciprofloxacin, had a less marked effect (a twofold increase), whereas the first-generation quinolone, nalidixic acid, did not affect the measured porphyrin concentration at all. The interference is probably due to the overlap in the emission fluorescence spectra of ofloxacin and urinary porphyrins at approximately 600 nm. To avoid a false-positive diagnosis of porphyria, we suggest using HPLC to separate ofloxacin (10-min retention time) from urinary porphyrins (which only start to elute at 12 min). Nonetheless, given a threefold increase in urinary porphyrins observed in the urine of an ofloxacin-treated patient, we also discuss a possible interference of the drug with the metabolism of porphyrins.
Aluminum determined in plasma and urine by atomic absorption spectroscopy with a transversely heated graphite atomizer furnace
Authors: Bradley C , Leung F Y
Published: January 2020

We compared a stabilized-temperature L'vov platform furnace containing an end-heated graphite atomizer (HGA) and transverse Zeeman background-correction system with a side-heated furnace system (transversely heated graphite atomizer; THGA) containing a longitudinal Zeeman background-correction system for the determination of aluminum in plasma and urine. The regression statistics for the correlation analysis of the two systems (slope coefficient = 0.995, intercept = -1.710, Sy/x = 0.021 micrograms/L) indicate that the systems generate comparable results. The newer technology of the THGA furnace with its more uniform and faster heating cycle allows a lower atomization temperature for aluminum, 2200 degrees C. Analyte carryover was significantly reduced in the THGA furnace system. The THGA system generates results equivalent to HGA in about one-third less time, thus making possible a greater throughput of samples in a busy laboratory.
Variability of laboratory coat resistance to blood strikethrough
Authors: Smith J W , Muzik A C , Lovitt S A , Nichols R L
Published: January 2020

Protection from contamination by potentially infectious fluids is an increasingly important aspect of hospital safety programs. Technical personnel in clinical laboratories may handle numerous samples of human blood and other fluids daily, and to protect themselves against exposure to bloodborne pathogens they routinely wear laboratory coats. We studied the effectiveness of six disposable (polypropylene; either spun-bond or spun-bond/melt-blown/spun-bond construction) and four reusable (polyester-cotton) laboratory coats in preventing blood passage. Fabrics (1018 samples) were tested at six time durations (1 s-5 min) and five pressures [1.7-13.8 kPa (0.25-2.0 psi)]. A standard spray test used to evaluate resistance to wetting showed that reusable coats were less repellent than disposables (P < 0.05). Pressure testing showed that reusable and spun-bond coats allowed greater blood passage than the spun-bond/melt-blown/spun-bond. Laboratory coats should be chosen that have sufficient resistance to blood or other body fluid passage for the task performed and for the period of time used.
Biological variation in urine samples used for analyte measurements
Authors: Ricós C , Jiménez C V , Hernández A , Simón M , Perich C , Alvarez V , Minchinela J , Maciá M
Published: January 2020

To determine the influence of biological variation on the reliability of data from different types of urine specimens, we measured nine analytes in first-morning, randomly collected, and 24-h samples of urine from 53 healthy individuals (14 men and 39 women). The urines were collected once a week for 10 weeks. The data obtained were used as a basis for specimen collection and to gain insight into the influence of urine quantities in the diagnosis, screening, and monitoring of patients. We found that 24-h urine expressed in output rather than concentration units is the most reliable specimen for diagnosis and monitoring for most of the analytes studied. On the basis of the ratio between estimated within- and between-subject variation, the tests with greatest medical usefulness for diagnosis and screening of specific pathologies are those measuring protein and sodium. Moreover, the results indicate that urine creatinine may be a poor test for diagnosis, monitoring, and screening.
Unexplained increase in serum digoxin: a case report
Authors: Doolittle M H , Lincoln K , Graves S W
Published: January 2020

We describe a patient with unexpectedly high serum digoxin after cardiac surgery. To control atrial fibrillation in the immediate postoperative period, she was given a brief trial of digoxin (four 0.25-mg doses) over 12 h. Serum digoxin 6 h later was 2.5 micrograms/L. Two days later, the patient developed ventricular fibrillation, which progressed to cardiac arrest. During or immediately after resuscitation, blood was drawn for a digoxin measurement, and the concentration reported was 9.3 micrograms/L; this result was verified by repeated analysis. Digoxin decreased rapidly and progressively to near 4.0 micrograms/L over the next several hours and thereafter decreased slowly to 1.0 microgram/L over the next 11 days, despite no digoxin being administered. The unexpectedly high digoxin raised questions about the accuracy of the digoxin measurement, particularly about the possible influence of the digoxin-like immunoreactive factor. Analytical approaches to distinguishing true digoxin from this factor and other artifacts of digoxin measurement were applied to this patient, with unanticipated results.
Clinical applications of gene therapy for cancer
Authors: Culver K W
Published: January 2020

The number of gene therapy protocols for the treatment of cancer is growing rapidly. The most common type of approved clinical trial for cancer gene therapy involves the ex vivo gene transfer of cytokine genes (e.g., tumor necrosis factor, interleukin-2, granulocyte-macrophage colony-stimulating factor) into tumor cells. The idea behind this approach is to use gene transfer to induce a patient's tumor to become more immunogenic. The genetically altered tumor cells are reinjected into the patient in an effort to induce a systemic antitumor immune response against residual tumor cells. In other trials, investigators are using in situ gene transfer to selectively destroy cancer cells, sparing normal tissues. Continuing advances in molecular biology are likely to allow the development of new cancer treatments and methods of cancer prevention that will redefine cancer therapy.
Diagnostic power of lecithin/sphingomyelin ratio and fluorescence polarization assays for respiratory distress syndrome compared by relative operating characteristic curves
Authors: Bender T M , Stone L R , Amenta J S
Published: January 2020

Amniotic fluids from 328 patients were analyzed for lecithin/sphingomyelin (L/S) ratio and surfactant/albumin (S/A) ratio by fluorescence polarization. Of this group, 61 neonates showed respiratory distress syndrome (RDS) on delivery within 3 days of testing. We compared the power of the L/S and S/A in diagnosing pulmonary maturity, using relative operating characteristic (ROC) curves. The area defined by the ROC curve of the S/A test exceeded the area defined by the L/S curve, but this difference was not statistically significant. The diagnostic power of the S/A test appears to be at least equal to that of the standard L/S test. A review of five cases of RDS in which laboratory tests had suggested maturity showed that neither the L/S nor the S/A could satisfactorily resolve the problem of false interpretations of maturity, particularly in mothers with diabetes mellitus who underwent cesarean section.
Eight compact analysis systems evaluated for measuring total cholesterol
Authors: Gregory L C , Duh S H , Christenson R H
Published: January 2020

We examined the analytical performance of eight compact systems for measuring total cholesterol: AccuMeter, Cobas Ready, Discovery f2, DT60, L-D-X, Reflotron, QCA, and Vision. We determined average bias at two decision levels, the mean absolute bias, and the percentage of results differing from the comparison method results by > 8.9% allowable total error limit for multiple reagent lots. Average bias was < 3% for all lots tested for AccuMeter, Discovery f2, and DT60, but > 3% for one or more lots or sample types tested with the other systems. Of results from each reagent lot, > 95% were within the 8.9% total error specifications with Discovery f2, DT60, and QCA, whereas the performance of L-D-X, Vision, and Reflotron depended on reagent lot and (or) sample type. Of all results from each lot tested with AccuMeter and Cobas Ready, > 5% exceeded the total allowable error limit. We determined imprecision for five systems: Cobas Ready, Discovery f2, and QCA had CVs < 3%, whereas CVs for AccuMeter and L-D-X were > 3% but < 5%.
Automated latex agglutination immunoassay of serum ferritin with a centrifugal analyzer
Authors: Simó J M , Joven J , Clivillé X , Sans T
Published: January 2020

A considerable demand for convenient, rapid, inexpensive assays of ferritin in serum has been generated in recent years in hospital laboratories and blood banks. We describe a simple and rapid particle-enhanced turbidimetric immunoassay suitable for routine application in a Monarch 2000 centrifugal analyzer with commercially available reagents. This fully automated assay (y) requires no pretreatment of sample, and correlation with a two-step sandwich ELISA (x) is excellent (y = 1.018x + 0.397, Sy/x = 0.027). The analytical range extends from 5 to 900 micrograms/L. Intraassay imprecision (CV) ranged from 1.1% to 5% for various specimen concentrations. Interassay imprecision ranged from 2.2% for above-normal concentrations (755 micrograms/L) to 9.5% for low concentrations (39 micrograms/L). No specimen-related carryover was detected. The method has been useful in our predeposit autologous blood transfusion program for rapid assessment of iron status in patients undergoing repeated phlebotomies.
Glycated protein update: implications of recent studies, including the diabetes control and complications trial
Authors: Benjamin R J , Sacks D B
Published: January 2020

On the basis of the results of the Diabetes Control and Complications Trial (DCCT), the American Diabetes Association (ADA) now recommends tight control of blood glucose to near-normal concentrations as the primary goal for most eligible insulin-dependent diabetic patients. In the DCCT, intensive therapeutic intervention was based on frequent self-monitoring of blood glucose and monthly measurements of glycohemoglobin. The importance of glycohemoglobin assessments serves to highlight the present inadequacies in laboratory measurements of this analyte, which hinders wide implementation of the ADA recommendations. Clinical interventions aimed at achieving the DCCT's published therapeutic goals may place patients at a significantly increased risk for life-threatening hypoglycemia, if the therapy is based on nonstandardized laboratory results. Clinical laboratories will now be under increasing pressure to provide reproducible, standardized measurements of glycohemoglobin, a goal that recent research has shown to be realistic, if widespread interlaboratory calibration is adopted. Finally, recent advances in measuring glycated serum proteins appear to warrant reevaluation of such assays during future intensive therapy trials, as potentially important tools for fine-tuning tight blood glucose control.
Radiolabeled polymerase chain reaction assay for detection of ras oncogene point mutations in tumors
Authors: Aoki Y , Lee J C , Pillai S , Isselbacher K J , Rustgi A K
Published: January 2020

The human ras gene plays a fundamental role in the transduction of extracellular signals to the nucleus, thereby regulating cell growth and differentiation. Point mutations in the ras gene convert it into a transforming oncogene that has been found in many solid and hematologic malignancies. We describe a rapid and sensitive assay based on a radiolabeled polymerase chain reaction followed by restriction enzyme digestion that we have adapted for differentiating between the wild-type and mutant ras genes. This assay should prove useful in the analysis of ras gene point mutations in clinical tumor specimens in which ras oncogene activation is an early event in carcinogenesis.
Effect of time between measurements on within-subject variability for total cholesterol and high-density lipoprotein cholesterol in women
Authors: Choudhury N , Wall P M , Truswell A S
Published: January 2020

A single blood cholesterol measurement may not accurately reflect an individual's true mean concentration. If duplicate blood samples are taken, what number of days between sampling gives the best chance of detecting the maximum within-subject variation? In this study, we analyzed 20 serial blood samples obtained from each of 13 healthy, menstruating women over 35 days. Variability was calculated as the semivariogram, which gives the average squared difference between replicate samples taken over a range of sampling intervals. Data were available for a complete set of intervals from 1 to 26 days. Variability in total cholesterol (TC) increased as the interval between sampling increased from 1 to 12 days. With high-density lipoprotein cholesterol (HDL-C), variability increased from 1- to 7-day intervals. In practice, our results suggest that, irrespective of the time of menstruation, the minimal interval for collecting a second blood sample for TC and HDL-C assays is approximately 2 weeks.
Process capability and stability of analytical systems assessed from proficiency testing data
Authors: Jenny R W
Published: January 2020

Participation in a proficiency testing (PT) program is a valuable adjunct to laboratory activities dedicated to the maintenance of reliable analytical methods. The PT program may facilitate continuous quality improvement if laboratory performance is presented in the context of expectations espoused by healthcare professionals for optimal patient care. Statistical process control (SPC) and capability analysis are tools used by industry in a Total Quality Management environment to characterize and monitor the performance of its processes relative to performance specifications. I conceptualized the use of an analytical system by many laboratories as a process that periodically produces results from the analysis of PT specimens. I treated a set of five PT results (theophylline) reported by a laboratory as a process sample and subjected the samples collected from many laboratories to SPC and capability analysis. The control charts--mean-(X-bar) and s-charts--produced by the analysis readily identify significant analytical errors in the context of peer performance and performance specifications provided by the regulatory program and analytical goal setting. The capability index (desirable Cp > 1.0) determined from clinical specification limits for the three analytical systems evaluated suggests an opportunity for improvement of laboratory performance.
Central role of zinc protoporphyrin in staging iron deficiency
Authors: Hastka J , Lasserre J J , Schwarzbeck A , Hehlmann R
Published: January 2020

In iron deficiency, zinc protoporphyrin (ZPP) is produced instead of heme, and the ZPP concentration in erythrocytes is increased (normal < or = 40 mumol/mol heme). We investigated the relevance of ZPP for staging iron deficiency. ZPP was determined by hematofluorometry in samples from 103 patients. Nineteen patients with iron depletion showed decreased serum ferritin (12.1 +/- 4.4 micrograms/L) with normal ZPP and hemoglobin (Hb). Twelve patients with iron-deficient erythropoiesis had decreased ferritin (10.4 +/- 2.4 micrograms/L), increased ZPP (72 +/- 9 mumol/mol heme), and normal Hb concentrations. In 72 patients with iron-deficiency anemia, ferritin was < 12 micrograms/L. In mild anemia (Hb between 100 and 120 g/L, and normal erythrocyte indices), ZPP was 100 +/- 16 mumol/mol heme. In severe anemia (Hb < 100 g/L, decreased erythrocyte indices), ZPP values were significantly higher (265 +/- 109 mumol/mol heme). We conclude that measurements of ZPP, ferritin, and Hb can reliably be combined to classify the degree of iron deficiency.
Mapping of antigenic sites in human neuron-specific enolase by expression subcloning
Authors: Quinn G B , Reeves I G , Day I N
Published: January 2020

Human serum neuron-specific enolase (NSE) is a marker of neurons and of small-cell carcinoma of the lung; improved immunoassays of NSE remain an important goal. Here, we used overlapping complementary DNA (cDNA) clones for reconstruction to express full-length recombinant NSE, and also to express a set of cloned subfragments through the prokaryotic expression vectors pUEX and pUBEX. Subfragments expressed as fusion proteins were used to characterize immunogenic and antigenic regions and epitopes and, expressed as affinity matrices, to derive purified, fractionated polyclonal antibodies. NSE epitope data can be visualized with yeast enolase-1 crystal structure coordinates: The two protein sequences align almost perfectly and are 61% identical. This approach demonstrates the complementarity of cDNA expression with techniques of polyclonal antiserum and monoclonal antibody production and with chemical peptide synthesis in the refinement of immunodiagnostic reagents.
Accuracy in clinical chemistry--does anybody care?
Authors: Tietz N W
Published: January 2020

The role of clinical chemistry in the diagnostic process has been enhanced by the evolution of better instrumentation and analytical techniques. The quality of some laboratory tests, however, has not kept pace with these advances. I present three examples--serum iron, serum lipase, and nonisotopic immunoassays--assays where some currently used methodologies are highly flawed. Causes for the less than optimal performance of some clinical laboratories are discussed.
Urinary iodide determined by paired-ion reversed-phase HPLC with electrochemical detection
Authors: Rendl J , Seybold S , Börner W
Published: January 2020

We propose an automated method for the routine analysis of urinary iodide, using paired-ion reversed-phase HPLC with electrochemical detection and a silver working electrode. Assay conditions include a flow rate of 1.0 mL/min and an operating potential of 0.10 V. The retention time for iodide is 5.4 min. Sample preparation can be semiautomated by use of a reduced-pressure manifold. The detection threshold (signal-to-noise ratio of 3) was 2 pmol, corresponding to 0.04 mumol/L. The within-run precision (CV) for a pooled urine sample was 3.9% at 452 nmol/L iodide. The average recovery of added iodine was 94%. For comparison with a colorimetric method, we measured 177 random (untimed) urine samples by both HPLC (y) and a Technicon AutoAnalyzer acid digestion method (x). After removal of organically bound iodine, the results for unbound urinary iodide determined by the two methods were nearly identical (r = 0.99; y = -0.03 + 1.00x; Sy/x = 0.12 mumol/L). Comparison of total urinary iodine measured by the Technicon AutoAnalyzer with unbound urinary iodide determined by HPLC also showed a high correlation (r = 0.96; y = -0.03 + 0.78x; Sy/x = 0.23 mumol/L), because iodine is excreted in urine mainly as iodide. We conclude that iodine in urine can be accurately determined by the more convenient HPLC assay.
Creatine kinase MB isoforms: sensitive markers of ischemic myocardial damage
Authors: Hossein-Nia M , Kallis P , Brown P A , Chester M R , Kaski J C , Murday A J , Treasure T , Holt D W
Published: January 2020

We investigated the use of creatine kinase (CK) MB isoforms as a marker of myocardial cell injury in a preliminary study of 16 patients with chronic stable angina after successful percutaneous transluminal coronary angioplasty (PTCA) and 25 patients after coronary artery bypass grafting (CABG). Three control groups were studied: apparently healthy volunteers (n = 31), patients undergoing thoracotomy (n = 10), and patients undergoing routine coronary angiography (n = 9). Patients in the PTCA group showed an association between ischemic ST segment changes lasting > 3 min and a transient increase in the MB2/MB1 ratio; however, all had total CK-MB activity within normal limits. Routine coronary angiography subjects had no significant change in MB2/MB1. In the CABG patients, MB2/MB1 peaked within 1 h after the cross-clamp release and returned to baseline by 24 h postoperatively. The median time to peak MM3/MM1 and total CK-MB activity was 2 and 8 h after reperfusion, respectively, returning to baseline values by 2 and 5 days, respectively. After thoracotomy, MB2/MB1 was increased only in elderly patients (n = 5) with risk factors for ischemic heart disease; total CK-MB activity was increased in only three of these. Apparently, CK-MB isoforms can detect myocardial damage in clinical settings with less overt damage than myocardial infarction.
Assessment of a simple colorimetric procedure to determine smoking status in diabetic subjects
Authors: Phillipou G , James S K , Seaborn C J , Phillips P J
Published: January 2020

The performance of a colorimetric assay for nicotine metabolites to validate self-reported smoking classification (nonsmoker, ex-smoker, and smoker) was assessed in a group of diabetic patients (n = 201). Comparison of the results with those of cotinine immunoassay (ELISA), by comparing respective areas under receiver operating characteristic curves, established the superiority of the cotinine immunoassay method. Adjusting the urinary concentrations of nicotine metabolites for creatinine excretion significantly lowered test performance. The sensitivity and specificity for the assay of nicotine metabolites to discriminate smoking classification within the diabetic patients at a threshold of > or = 28 mumol/L "cotinine carboxylic acid equivalents" were 68.4% and 98.6%, respectively; the corresponding sensitivity and specificity for urinary cotinine at a cutoff of > or = 0.5 mumol/L were 94.7% and 100%. The low sensitivity of the colorimetric urinary nicotine metabolites assay precludes its application as an objective assessment of smoking status in our patient population.
Simultaneous measurement of cocaine, cocaethylene, their metabolites, and "crack" pyrolysis products by gas chromatography-mass spectrometry
Authors: Cone E J , Hillsgrove M , Darwin W D
Published: January 2020

We developed a sensitive and specific assay for the simultaneous measurement of cocaine, cocaethylene, six of their metabolites, and anhydroecgonine methyl ester, a pyrolysis product, in biological fluids. The assay involves solid-phase extraction columns containing a copolymeric bonded phase for isolation of cocaine analytes, derivatization with N,O-bis(trimethylsilyl)trifluoroacetamide and 10 g/L trimethylchlorosilane, and measurement with gas chromatography-mass spectrometry operating in the selected-ion monitoring mode. Detector responses for analytes were linear over a concentration range of 3.1-1000 micrograms/L. The limits of detection were approximately 1 microgram/L for cocaine, ecgonine methyl ester, and benzoylecgonine and 3-6 micrograms/L for the remaining analytes. Hydrolysis of cocaine and artifact formation of anhydroecogonine methyl ester during extraction and assay was < 1%. Cocaine and its derivatives appear in different proportions in plasma, saliva, and urine according to the biological fluid and time of measurement. Each biological fluid provides unique information on the disposition of cocaine in human subjects.
Glycohemoglobin measured by automated affinity HPLC correlates with both short-term and long-term antecedent glycemia
Authors: Cefalu W T , Wang Z Q , Bell-Farrow A , Kiger F D , Izlar C
Published: January 2020

We evaluated glycohemoglobin (GHb) and glycated plasma protein (GPP) by automated affinity HPLC for their ability to monitor both short-term and long-term antecedent glycemia in 70 diabetic subjects. We placed 30 subjects on an intervention protocol in which insulin and (or) dietary changes were made twice weekly to acutely decrease glycemia. We monitored 40 subjects at 6-week intervals; changes in the clinical regimen were made at that time only. Despite weekly changes in mean blood glucose in the subjects who received more intensive intervention. GHb concentrations correlated significantly with the weekly (r = 0.66, P < 0.001), 2-week (r = 0.70, P < 0.001), 3-week (r = 0.72, P < 0.001), and 6-week (r = 0.83, P < 0.001) mean glucose concentrations. GPP correlated significantly with measured glycated albumin determined by boronate affinity columns (r = 0.83, P < .001) and correlated best with the 1-week (r = 0.66, P < 0.001), 2-week (r = 0.64, P < .001) and 3-week (r = 0.60, P < 0.001) mean antecedent glucose concentration. Thus, GHb, traditionally considered a marker for only long-term diabetic control, correlated significantly with both short-term and long-term antecedent glycemia.
Stability of plasma lactate in vitro in the presence of antiglycolytic agents
Authors: Astles R , Williams C P , Sedor F
Published: January 2020

The use of plasma lactate to assess metabolic or circulatory impairment requires definition of critical preanalytical and analytical parameters. Stability has been documented for only 15 min after acquisition when samples were collected with fluoride and transported on ice. We examined time elapsed before analysis, storage temperature, and the antiglycolytic agent used to define preanalytical conditions. Plasma lactate was measured with a Kodak Ektachem 700XR analyzer. In controlled studies on volunteers, storage on ice slowed but did not eliminate the production of lactate; for samples collected with sodium fluoride (F) and potassium oxalate (OX), lactate increased by 0.2 mmol/L after 1 h, then changed little regardless of the storage temperature. For patients' samples collected in F/OX, the mean increase was only 0.15 mmol/L after 24 h. Samples with leukocytosis (neutrophil counts 23 x 10(9)-52 x 10(9)/L) were also stable, with a mean increase of 0.3 mmol/L at 8 h. Use of the antiglycolytic agents F and OX (at 60 and 12 mmol/L, respectively) maintained apparently stable lactate concentrations at room temperature for up to 8 h without special handling.