bluuebunny/crossref_metadata_2025 huggingface dataset:
Dry electrolyte-balanced heparinized syringes evaluated for determining ionized calcium and other electrolytes in whole blood
Authors: Toffaletti J , Ernst P , Hunt P , Abrams B
Published: January 2020

By analyzing whole blood containing no anticoagulants (uncoagulated whole blood) immediately after collection, we evaluated the relative changes in the concentrations of ionized calcium and other electrolytes in whole blood collected in dry heparinized syringes and in serum prepared from blood collected in evacuated blood-collection tubes. Using these dry heparinized syringes, we collected and analyzed whole blood that contained either 33 or 13 int. units of lithium heparin or 40 int. units of electrolyte-balanced heparin per milliliter of blood. We evaluated the effects both of these heparins at different concentrations of ionized calcium and of the incomplete filling of the syringes. We conclude that: (a) when analyzed within 2-3 min after collection, uncoagulated whole blood provides ionized calcium results unaffected by anticoagulants or cellular metabolism; (b) the preparation of serum unpredictably changes ionized calcium; (c) the use of dry electrolyte-balanced heparin virtually eliminates the interference in ionized calcium concentrations between 0.9 and 1.6 mmol/L; and (d) incomplete filling of electrolyte-balanced heparinized syringes produces no effect in syringes two-thirds full (60 int. units/mL heparin concentration) and a small effect in syringes one-third full (120 int. units/mL heparin).
Enzymatic method for measuring ethylene glycol with a centrifugal analyzer
Authors: Standefer J , Blackwell W
Published: January 2020

We describe a semiautomated, enzymatic method of analysis for ethylene glycol in plasma. Glycerol dehydrogenase (EC 1.1.1.6) from Enterobacter aerogenes, which has high specificity for ethylene glycol, is mixed with 3 microL of specimen in a centrifugal analyzer. NAD+ is added to initiate the reaction, and 450 s after an initial 90-s delay, the absorbance at 340 nm is measured. Monthly calibration with a five-point calibration curve is sufficient to provide between-day precision (CV) of 2% to 5%. The detection limit is 0.3 mmol/L with a CV of 10%. There is no significant interference from ethanol, methanol, isopropanol, acetone, lactate, or glycerol.
Major disagreements between immunoassays of carcinoembryonic antigen may be caused by nonspecific cross-reacting antigen 2 (NCA-2)
Authors: Börmer O P
Published: January 2020

Four "sandwich"-type immunoassays of carcinoembryonic antigen (CEA) based on the use of monoclonal antibodies (Abbott CEA-RIA Monoclonal, Pharmacia/Wallac Delfia CEA kit, Roche CEA EIA Duomab 60, and our in-house immunoradiometric assay) were tested for cross-reaction with nonspecific cross-reacting antigen 2 (NCA-2) in meconium. The Roche assay did not react with NCA-2, but the other three assays cross-reacted strongly and to about the same extent with this antigen. NCA-2 is the CEA gene family member that is structurally most similar to CEA, and other authors have found by indirect evidence that this antigen also is increased in the serum of many cancer patients. In a previous study we found that the Roche assay yielded lower mean values than the other assays for CEA in serum from colorectal cancer patients. Furthermore, the correlation between the Roche CEA values and those of each of the other three assays was weaker than the correlation between these NCA-2 cross-reactive assays. We conclude that these results can be explained by the different cross-reactivity with NCA-2 of the antibodies used by the various assays, as described here. Our findings raise interesting questions regarding the possible role of NCA-2 as a tumor marker.
Immunoreactivity of plasma parathyrin-related peptide: three region-specific radioimmunoassays and a two-site immunoradiometric assay compared
Authors: Ratcliffe W A , Norbury S , Stott R A , Heath D A , Ratcliffe J G
Published: January 2020

We measured parathyrin (parathyroid hormone)-related peptide (PTHRP) in plasma by three region-specific RIAs and compared them with an established two-site immunoradiometric assay (IRMA) of PTHRP1-86 in samples from control subjects and from patients with primary hyperparathyroidism (PH) and humoral hypercalcemia of malignancy (HHM). The two direct RIAs of PTHRP1-34 and PTHRP37-67 were specific for regions 9-18 and 52-61, respectively. In the extraction RIA of PTHRP1-34 we used an affinity gel containing a monoclonal antibody specific for the 17-27 sequence; cross-reacting PTHRP species eluted from the gel were assayed by the RIA of PTHRP1-34. PTHRP1-86 plasma concentrations by IRMA were less than 0.23 pmol/L in control subjects and patients with PH, and were significantly increased in patients with HHM (mean 6.1 pmol/L, P less than 0.001). In contrast, plasma PTHRP1-34 concentrations were not significantly different in the three groups; in HHM patients, the mean was 190 pmol/L. Plasma PTHRP37-67 concentrations were similar in control and PH groups and, although significantly increased in HHM patients (mean 440 pmol/L, P less than 0.002), showed poor diagnostic discrimination. PTHRP1-34 concentrations after affinity extraction of plasma were also significantly higher in HHM patients (mean 10.7 pmol/L, P less than 0.001), but showed incomplete diagnostic discrimination. We conclude that the diagnostic utility of the direct RIAs for quantifying PTHRP is markedly inferior to the IRMA of PTHRP1-86.
Adreno-medullary hypertension: a review of syndromes, pathophysiology, diagnosis, and treatment
Authors: Krakoff L R , Garbowit D
Published: January 2020

Hypertension may be attributable to various disorders involving the central or peripheral adrenergic (catecholamine) pathways. Pheochromocytoma is the best known of these disorders, but many syndromes mimic the clinical features of this tumor. In adreno-medullary hypertension, cardiovascular tissues are stimulated by activation of alpha or beta adrenergic receptors, or both. Specific diagnosis of adreno-medullary hypertension depends on careful clinical assessment and selection of sensitive and specific biochemical tests for measuring the catecholamines and their principal metabolites in urine or plasma. If such tests indicate the presence of a chromaffin cell neoplasm, accurate localization (imaging) is provided by computed axial tomography (CAT) or magnetic resonance imaging (MRI). Adreno-medullary hypertension is effectively controlled, pharmacologically, by alpha and beta receptor antagonists, which may be given intravenously for emergencies. Excess catecholamine synthesis by pheochromocytomas can be reduced by methyltyrosine. Surgical cure of pheochromocytomas can be expected in most instances, but long-term surveillance for recurrent tumors, some of which may be malignant, is needed. Chemotherapy can reduce the tumor bulk of a malignant pheochromocytoma. Recent use of molecular biology techniques may be helpful in early detection of malignant transformation.
Advances in catecholamine and metabolite measurements for diagnosis of pheochromocytoma
Authors: Rosano T G , Swift T A , Hayes L W
Published: January 2020

Assessment of catecholamine production and excretion is important in the laboratory detection of pheochromocytoma, a rare but curable cause of hypertension. Advances in catecholamine and metabolite methodologies have enhanced the diagnostic acumen by increasing analytical sensitivity and eliminating many of the interferences observed with earlier methods. Estimation of urinary catecholamines metanephrine and vanillylmandelic acid is routinely used in the biochemical detection of pheochromocytoma and in monitoring the completeness of tumor excision as well as the possibility of recurrence. Traditional spectrophotometric and fluorometric methods for urinary catecholamines and their metabolites are being replaced by highly sensitive and selective chromatographic methods. The ability to quantify individual catecholamines and metanephrines by high-performance liquid chromatography is of particular value for detecting familial forms of the tumor that may secrete epinephrine. Plasma norepinephrine and epinephrine measurements are of additional diagnostic value in determining recent catecholamine release and response to clonidine suppression. For either urine or plasma measurements, appropriate patient preparation, sample collection, and method validation along with an understanding of the variable pattern of catecholamine secretion and metabolism in pheochromocytoma are essential. Advances in laboratory methodology and reference intervals for catecholamines for clinical interpretation are reviewed.
Applications of ambulatory blood pressure monitoring in clinical practice
Authors: Weber M A , Smith D H , Neutel J M , Cheung D G
Published: January 2020

Traditionally, blood pressure has been measured by the sphygmomanometer in the medical office. There is growing evidence, however, that office blood pressures may not be typical of values throughout the day. Between 20% and 30% of patients diagnosed with hypertension in the office actually are normotensive at other times. Ambulatory blood pressure monitoring with small, portable devices that automatically measure blood pressure every few minutes throughout the day appears to be an appropriate tool when "white-coat" hypertension is suspected--i.e., for individuals whose hypertension in the physician's office is not associated with other physical or historical evidence for cardiovascular disease or with other risk factors. Used prudently, ambulatory monitoring is a cost-effective technique that potentially can prevent unnecessary treatment of patients. Moreover, whole-day measurements may correlate more closely than office measurements may correlate more closely than office measurements do with findings of cardiovascular disease. This new approach also has highlighted the circadian pattern of blood pressure, especially the sharp early to mid-morning increase that coincides with an increased tendency to major cardiovascular events. This has focused attention on directing antihypertensive therapy towards the morning hours. Ambulatory monitoring is now used routinely in studies of antihypertensive drugs. This technique has no placebo effect and takes fewer patients to assess drug efficacy than do conventional methods.
Temperature-dependent immunoreactive assay to screen for digoxin-like immunoreactive factor(s)
Authors: Guédeney X , Chanez C , Grenier A , Scherrmann J M
Published: January 2020

Endogenous circulating digoxin-like immunoreactive factors (DLIF) are known to cross-react with antibodies to digoxin and to inhibit Na+/K(+)-transporting ATPase (Na+K+ATPase; EC 3.6.1.37). Moreover, increasing the immunoassay temperature from 4 to 37 degrees C markedly decreases DLIF from human cord serum. We tested several compounds, including hormonal steroids, bile salts, lipids, and methionine-enkephalin, for their ability to cross-react with two commercially available 125I digoxin RIAs, to inhibit porcine Na+K+ATPase, and to see whether they present the same incubation temperature dependence as human cord serum. Except for methionine-enkephalin, all compounds were inhibitors of Na+K+ATPase in the range of 1-10 mmol/L. Progesterone exhibited the highest cross-reactivity in the two RIAs. The apparent digoxin immunoreactivity for the majority of the cross-reacting steroids, bile salts, and linoleic acid was markedly decreased by increasing the incubation temperature from 4 to 37 degrees C, whereas estriol, pregnanediol, and nonspecific compounds (e.g., ethanol, human serum albumin) did not appear to be temperature-sensitive. Both lysophosphatidyl lipids gave an increased apparent digoxin concentration with increasing incubation temperature. Our data suggest that numerous weakly cross-reactive compounds can parallel the response of human cord serum. However, the temperature-dependent effect could be an additional criterion for identifying DLIF.
Lactate dehydrogenase, creatine kinase, and their isoenzymes in pleural effusions
Authors: Paavonen T , Liippo K , Aronen H , Kiistala U
Published: January 2020

Lactate dehydrogenase (LD; EC 1.1.1.27) and creatine kinase (CK; EC 2.7.3.2) are widely distributed cytoplasmic enzymes. LD has five and CK has three isoenzymes distributed in different proportions in various tissues. The amounts of LD and CK and the distribution of isoenzymes in different body fluids are not thoroughly characterized. We have measured the total LD and CK concentrations and their isoenzyme distribution in pleural aspirates and in serum from 22 patients with benign conditions and from 14 patients with malignant effusions. In malignant pleural fluid, the mean total LD was 662 U/L; in benign conditions, it was nearly 5840 U/L with large variations (91-43 400 U/L) according to clinical diagnosis, the highest values being reached in inflammatory lesions. The mean total CK concentration in pleural fluid was close to the serum value in both groups of patients, as was the pleural CK isoenzyme distribution. The LD isoenzyme distribution in pleural effusions differed from that in serum in both groups, with LD-4 and -5 being the main isoenzymes in their pleural fluid specimens (greater than 42% of total LD). The total LD concentration correlated somewhat (r = 0.57) with the total pleural protein content. In conclusion, the pleural LD isoenzyme distribution, both in benign and malignant conditions, differs from that in serum, having shifted towards more anaerobic and embryonic isoenzymes (LD-4 and -5). Moreover, the greater the concentration of pleural total LD, the greater the proportion of LD-4 and -5. These data suggest that visceral or parietal pleural cells are rich in LD isoenzymes 4 and 5.
Use of immunoglobulin heavy-chain and light-chain measurements in a multicenter trial to investigate monoclonal components: II. Classification by use of computer-based algorithms
Authors: Jones R G , Aguzzi F , Bienvenu J , Gasparro C , Bergami M R , Bianchi P , Perinet A , Penn G , Keller I , Whicher J T
Published: January 2020

We describe a computer algorithm for classifying serum monoclonal proteins (MC) based on serum protein electrophoresis (SPE) and the automated measurement of kappa and lambda light chains and IgG, IgA, and IgM. We developed the algorithm by using a large database of unselected samples containing MC collected in a multicenter study. The performance of the algorithm was optimized by using iterative computational procedures and was tested on both the development database and on an independent set of MC-containing samples. With the development database, the algorithm correctly classified 50% and misassigned 2.5% of the MC. Where the MC were present in concentrations greater than 10 g/L, the rate of successful classification increased to 72% with 3% misclassification. When the algorithm was tested on a group of 101 MC-containing samples from an independent source, 67% were correctly classified and 8% misclassified, half of the latter being unusual IgD myelomas. We discuss the scope for the application of the algorithm in routine laboratory practice involving personal computer software.
Cholesterol operational process specifications for assuring the quality required by CLIA proficiency testing
Authors: Westgard J O , Wiebe D A
Published: January 2020

Current U.S. governmental regulations and requirements for the quality of laboratory tests do not provide a consistent form, comparable numbers, or practical specifications for the routine operation of laboratory testing processes. For cholesterol, as an example, the Health Care Financing Administration provides an analytical performance criterion for proficiency testing to enforce the Clinical Laboratory Improvement Act (CLIA), whereas the U.S. National Cholesterol Education Program (NCEP) provides clinical guidelines for test interpretation, as well as analytical goals for imprecision and inaccuracy. Routine operating process specifications for imprecision, inaccuracy, and quality control can be derived from the analytical and clinical requirements for quality. Use of an analytical "total error" model and a clinical "decision interval" model provides logically consistent and numerically comparable specifications. Studies with these coherent models indicate that a cholesterol testing process properly planned to satisfy the CLIA analytical requirement will also satisfy the NCEP clinical requirement. To provide 90% assurance of detecting systematic shifts of a magnitude that would cause the CLIA analytical requirement to be exceeded, the operational specifications for a cholesterol testing process are an allowable CV of less than or equal to 2%, an allowable bias of less than or equal to 1%, and a control procedure with two measurements per run interpreted by 1(3)s, 1(2.5)s, or 1(3)s/2(2)s/R4s control rules.
Rapid, semi-quantitative assay of C-reactive protein evaluated
Authors: Vallance H , Lockitch G
Published: January 2020

We evaluated a new rapid semi-quantitative immunometric assay of C-reactive protein (CRP) as a screening test for sepsis by comparison with an automated nephelometric method. Plasma samples (n = 101) from preterm infants during the first week of life were saved for CRP analyses. We measured CRP by the Nycocard semiquantitative method and compared the results with those obtained with a Behring Nephelometer. A CRP value less than 10 mg/L was considered to be negative for infection. All CRP results read as less than 10 mg/L (negative) by the Nycocard method were also less than 10 mg/L by the comparison method, and all CRP values found to be greater than 20 mg/L (positive) by the Nycocard method were also positive by the comparison method. Results in the 10-20 mg/L range were considered equivocal. We conclude that the Nycocard CRP semi-quantitative method is a rapid and useful screening test for sepsis in preterm infants.
Rapid diagnosis of familial defective apolipoprotein B-100 by Amplification Refractory Mutation System
Authors: Wenham P R , Newton C R , Houlston R S , Price W H
Published: January 2020

We report a method for the diagnosis of familial defective apolipoprotein (apo) B-100, using the Amplification Refractory Mutation System (ARMS) and either whole blood or extracted DNA in the polymerase chain reaction. Normal and mutant alleles are identified by using two allele-specific oligonucleotide primers, each with the same common primer, to amplify a 187-bp fragment of the apo B-100 gene. Fragment amplification occurs only when the allele-specific primer matches the nucleotide sequence of the template DNA. The amplification product is detected by agarose gel electrophoresis, followed by staining with ethidium bromide. The technique is simple, reliable, and robust. It avoids the use of radiation or hybridization with allele-specific oligonucleotide probes, and is well suited for use in the routine clinical chemistry department.
Chemiluminescence immunoassay of aldosterone in serum
Authors: Stabler T V , Siegel A L
Published: January 2020

A chemiluminescence immunoassay (CLI) for the direct measurement of aldosterone in serum was developed with aminobutylethyl isoluminol (ABEI) as the label. In this competitive assay the samples are incubated with sample, antibody, aldosterone-carboxymethyl oxime-ABEI, and paramagnetic particles coated with second antibody. After magnetic separation and washing, the samples are incubated with 200 microL of NaOH (2 mol/L) at 60 degrees C for 30 min. In the luminometer the chemiluminescence is produced by the serial injection of 150 microL each of microperoxidase and H2O2 solutions. Comparison of results with an RIA method showed excellent agreement: CLI = 1.001 RIA + 0.020 (r = 0.99, n = 93). The method is simple and avoids the hazards and costs associated with isotopic waste. The label has a shelf life of at least two years.
31P nuclear magnetic resonance and zero-point titration compared for measuring free magnesium concentration in erythrocytes
Authors: Geven W B , Vogels-Mentink G M , Willems J L , v Os C H , Hilbers C W , Joordens J J M , Rijksen G , Monnens L A H
Published: January 2020

Intracellular ionized magnesium concentrations ([Mg2+]i) were measured in erythrocytes by 31P nuclear magnetic resonance (NMR) and zero-point titration in 14 controls and seven patients with renal magnesium loss. The mean intracellular ionized magnesium concentration in controls measured by 31P NMR was 0.20 (SD 0.03) mmol/L cell water, compared with 0.55 (SD 0.12) mmol/L cell water by zero-point titration. Total erythrocyte magnesium content measured with the lysate method was 0.63 mmol/L cell water higher than estimated by 31P NMR, probably because not all magnesium complexes are fully visible to the NMR technique. We found a positive correlation between plasma ultrafiltrable magnesium and [Mg2+]i irrespective of the [Mg2+]i assay used. [Mg2+]i measured with 31P NMR correlated modestly but significantly with [Mg2+]i determined by zero-point titration (r = 0.58, P less than 0.02). Washing erythrocytes before the zero-point titration decreased the ATP content and the cell water fraction, which led to overestimation of [Mg2+]i by zero-point titration. Although absolute values for [Mg2+]i differ with the assay used, both methods determined significantly lower values for [Mg2+]i in patients with isolated renal magnesium loss.
Concentrations of high-density lipoprotein subfraction HDL2 and lipoprotein A-I in a random population of healthy subjects
Authors: Roche D , Migueres M L , Lequang N T , Burstein M , Ekindjian O G , Girard-Globa A
Published: January 2020

High-density lipoproteins (HDL) are now currently subdivided according either to density and size—HDL2 and HDL3—or to surface apoprotein composition—lipoprotein A-I (LpA-I) without A-II, and LpA-I:A-II. In samples from blood bank donors (60 women, 47 men), we evaluated HDL subclasses, LpA-I particles, and other classic risk factors for atherosclerosis and compared them with each other. We found a good correlation between HDL2 and LpA-I (r = 0.74, P < 0.001), the correlation being more marked in women (r = 0.74) than in men (r = 0.67). LpA-I was also strongly correlated with total apolipoprotein A-I (apoA-I) (r = 0.61), which suggests that LpA-I represents a significant portion of the variable pool of apoA-I. By contrast, LpA-I:A-II but not LpA-I was correlated with HDL3, confirming the preferential association of LpA-I with HDL2. The difference between the sexes was more marked for HDL2 (+66% in women) than for LpA-I (+25%). We conclude that in normolipemic subjects the size of the HDL2 pool depends on that of LpA-I. Considering the speed and low cost of the assay, determination of HDL2 cholesterol might be a useful tool for assessing cardiovascular risk.
Measurement of Porphobilinogen in Urine by a Simple Resin Method with Use of a Surrogate Standard
Authors: Buttery Joseph E , Stuart Sandra
Published: January 2020

In this method for urinary porphobilinogen (PBG), urine is added to Bio-Rad AG1-X2 (200–400 mesh) acetate resin under alkaline conditions and mixed. After two water washes, the adsorbed PBG is eluted with acid and reacted with Ehrlich's reagent (p-dimethylaminobenzaldehyde). Quantification is by comparison of the color developed with that of a PBG standard similarly treated or of a calibrated methyl red solution. The precision of assay of PBG at 20 and 50 μmol/L is 1.4% and 0.9% within-batch and 4% and 3.9% between-batch, respectively. The analytical recovery is about 90%, a proportion that appears to be inherent in the resin method. The proposed method (y) agreed well with the method of Mauzerall and Granick (x; J Biol Chem 1956;19:435–46), yielding the regression equation y = 0.957x + 2.9 (r = 0.993, n = 26). Good agreement was achieved with results determined from the PBG and the methyl red standards. The proposed method is inexpensive, simple to perform, and suitable for routine and emergency use.
Effect of protein concentration on the formation of glycated albumin and fructosamine
Authors: Lamb E , Mainwaring-Burton R , Dawnay A
Published: January 2020

Considerable debate surrounds the question of whether fructosamine concentration should be corrected for serum protein concentration (see 1 for review). Staley (2) has argued against such correction, given that, theoretically, glucose concentration is the rate-limiting step in the glycation reaction; i.e., available lysine residues willalways be in excess of reactive open-chain (carbonyl) glucose molecules, which are only 0.001% of the total (3). However, because the open-chain and cyclic forms of glucose exist in freely exchangeable equilibrium, we conjectured that, as carbonyl glucoses were removed by glycation, more glucose molecules would rapidly isomerize to the open-chainform to maintain the equilibrium, if so, then protein concentration would also be an important factor in determining the glycation rate.
Simple, Rapid Detection of PCR Heteroduplexes in DNA Mutations and Polymorphisms
Authors: Surh Linda C , Shutler Gary G , Korneluk Robert G
Published: January 2020

Detection of nucleotide differences is fundamental among diverse procedures used to study DNA mutations and polymorphisms, whether for basic molecular research or for diagnosis of genetic disorders. Rapid and efficient analysis without radioactive, chemical, or enzymatic modification is currently possible when polymerase chain reaction (PCR) products are electrophoresed on small polyacrylamide gels (5.0 cm × 4.3 cm × 0.45 mm) and stained with silver. The PhastSystemmTM (Pharmacia LKB Biotechnology, Uppsala, Sweden) was initially developed for protein electrophoresis/isoelectric focusing (1) and involves horizontal electrophoresis with an automated staining unit. We have adapted this system to heteroduplex formation of nucleic acids to detect the most frequent mutation in cystic fibrosis (CF), designated ΔF508 (2). This system offers the advantages and uniformity of semi-automated polyacrylamide electrophoresis in a DNA clinical laboratory and the convenience of precast polyacrylamide gels, rapid electrophoretic times (<30 min), and an automated developing chamber where picogram quantities of DNA can be reproducibly silver-stained. Because pre-packaged agarose buffer strips are used, one need not prepare buffer solutions.
Specific measurement of cyclosporine concentrations in whole blood: radioimmunoassay and fluorescence polarization immunoassay compared
Authors: Fuller Kathleen A , Brown Wayne S , Koenig John W , Eveland Barbara J , Scott Mitchell G
Published: January 2020

Letters

A 39-year-old woman with a 20-year history of hypothyroidism caused by Hashimoto thyroiditis had been managed adequately with oral thyroxun (T4), 200 mg/day, until a few months before referral, at which time she developed symptoms of hyperthyroidism. Her thyroid hormone proffle at the time of referral is shown in Table 1 (Sample 1). Her normal value for serum thyrotropin (TSH) concentration indicates that she was euthyreid but, because of the high serum triiodothyronune (T3) value, the daily oral doseof T4 was decreased to 100 mg. The serum thyroid tests were repeated four weeks later (Table 1, Sample 2): The decreased T4 and increased TSH show that the patient had become hypothyroid at this dosagé of T4 but the serum T3 concentration was still in the high normal range.
False-Positive Titers of Thyroid Autoantibodies in Patients Undergoing Hemodialysis?
Authors: Lukinac Ljerka , Kusic Zvonko , Kes Petar
Published: January 2020

Concentrations of thyroid-related hormones in serum of patients with chronic renal failure are known to be abnormal (1, 2). In our study on thyroid-function testing of patients undergoing hemodialysis, we determined, in addition to concentrations of free and total triiodothyronine, free and total thyroxin, “reverse” triiodothyronine, and thyroxin-binding globulin, the titers of thyroglobulin and microsomal autoantibodies (TGA and TMA, respectively). The study was provoked by the appearance of an uncommon agglutination pattern in the control wells of some samples from patients with chronic renal failure during the standard procedures of detecting TGA and TMA with hemagglutination methods (Thymune-T and Thymune-M assays from Welcome, London, U.K.). For these samples we were not certain whether positive titers for TGA and (or) TMA represented false-positive or true-positive values. Therefore, we assayed the absorbed serum samples and samples after addition of excess nonspecific immunoglobulin. Furthermore, we wanted to determine the difference in TGA and TMA titers of serum samples before and after hemodialysis.
Interferences with Determination of 17-Hydroxyprogesterone in Amniotic Fluid
Authors: Plavšić V , Rogić D , Dumić M , Ille J , Brkljačić Lj , Latin V
Published: January 2020

Continuing our work on the problems of congenital adrenal hyperplasia (CAH) (1, 2), we have established reference values for 17-hydroxyprogesterone (17-OHP) and androstenedione (Δ4) in amniotic fluid(AF) and done 12 successful prenatal diagnoses in families at risk for CAH (3). 17-OHP was determined in the AFs of 105 women in the second trimester of pregnancy with a kit from Sorin-Biomedica (Saluggia, Italy; tritium-labeled 17-OHP, ether extraction). In another 80 pregnant women, 17-OHP was determined with a new Sorin-Biomedica kit (iodine-labeled 17-OHP, ether extraction); a DPC Coat-A-Count kit (Diagnostic Products Corp., Los Angeles, CA), with and without ether extraction; and a CIS Bio International (Gif-sur-Yvette Cedex, France) coated-tubes kit, with and without ether extraction(Table 1).
Discrepancies between methods for amylase in cases of macroamylasemia
Authors: Cobbaert Christa
Published: January 2020

Macroamylasemia is often accompanied by hyperamylasemia and, because naturally occurring macroamylases (e.g., immunoglobulin-bound macroamylases) are usually indistingmshable from normal P- and S-amylases in conventional quantitative amylase assays, the major clinical importance of macroamylase lies in its potential to create confusion during the investigation of possible pancreatitis.
Storage of Methane Breath-Test Samples in Plastic Syringes
Authors: Khin Myo , Genge James R , Bolin Terry D , Htain Win
Published: January 2020

In using gas-chromatographic measurement of breath methane and investigating its relationship to various carbohydrate malabsorption conditions (1,2), breath samples often have to be stored for considerable lengths of time before analysis. Foil gas envelopes, rubber-stoppered glass tubes (Vacutainer Tubes; Becton Dickinson, Rutherford, NJ 07070), and disposable plastic syringes may all be used. The advisability of using glass tubes has recently been questioned (3), after observation of contamination of sterilized, silicone-coated VacutainerTubes with methane. Plasticsyringes would appear to be the most convenient alternative when storage of large sample volumes is required. Because ofthe increase in breath-methane analysis tests used in population surveys and field studies, we examined the limits of storage of methane samples in plastic, disposable 30-mL syringes.
Analytical goals for determinations of theophylline concentration in serum
Authors: Jenny Richard W
Published: January 2020

Statistical principles for analytical goal-setting were applied to two medical applications of drug-monitoring data: (a) individualizing dosage requirements by reference to a population-based therapeutic range or to a patient-specific decision value determined by Bayesian decision analysis, and (b) prospective dosing by using pharmaco-kinetic principles. For application a, the analytical goal for total allowable analytical error (TE) was defined as the amount of error that does not decrease by more than 5% either the sensitivity (probability) for detecting dosage regimens that may require modification or the specificity for detecting appropriately dosed patients. The limiting factor in achievable sensitivity and specificity was the intra-individual variation of peak steady-state concentration (Css), with the TE determined to be a CV of 4%. For application b, error-propagation rules were applied to a proposed prospective dosing scheme (J Pharmacokinet Biopharm 1978;6:135-51). The TE was determined to depend on the rate of theophylline clearance. For clearance rates less than or equal to 0.6 mL/(kg.min), the TE (CV) must not exceed 3% if the predicted infusion rate is to produce, with 95% confidence, a concentration within the therapeutic range.
Methadone concentrations in plasma and their relationship to drug dosage
Authors: Wolff Kim , Sanderson Marion , Hay Alastalr W , Raistrick Duncan
Published: January 2020

We have developed a sensitive HPLC method for measuring methadone in plasma and have used it to establish that there is a linear relationship between plasma concentration and methadone dose over the range of 3-100 mg of methadone per day in a group of 31 addicts. We found a good correlation between dose and plasma concentration (r = 0.89), with the plasma methadone concentration increasing by 0.263 mg/L for every milligram of methadone consumed per kilogram of body weight. Five patients had unexpected high or low concentrations; this finding is discussed.
Use of a synthetic soluble bilirubin derivative to assess interference in creatinine measurements
Authors: Franzini Carlo , Morelli Anna M , Cattozzo Glanpaolo
Published: January 2020

In assessing interference from bilirubin, the use of a synthetic soluble derivative (ditaurobilirubin, DTB) is recommended as a surrogate for the natural conjugates (Bc). We compared the interference effect of unconjugated bilirubin (Bu), Bc, and DTB, using six mechanized methods for serum creatinine measurement. No significant interference was noted in methods that include removal of proteins or in an enzymatic method involving NADH oxidation. Heavy (negative) interference was observed in an alkaline picrate method, and in direct enzymatic methods based on hydrogen peroxide measurement: interference was always more pronounced in the presence of the two soluble derivatives (Bc and DTB), whose interference was of the same magnitude. These results point out the utility of testing for bilirubin interference by using soluble derivatives, in addition to Bu, and suggest the feasibility of using DTB as a surrogate for Bc for this purpose.
Analysis of apolipoprotein E genotypes by the Amplification Refractory Mutation System
Authors: Wenham PhIlIp R , Newton ClIve R , Price WillIam H
Published: January 2020

The Amplification Refractory Mutation System (ARMS) has been successfully applied to the detection of apolipoprotein (apo) E genotypes in human DNA extracted from peripheral blood. By using four allele-specific oligonucleotide primers and one common primer, one can identify the three common alleles of the apo E genetic polymorphism, epsilon 2, epsilon 3, and epsilon 4. The system amplifies two sequences of the apo E gene, one of 181 bp and the other 319 bp. These sequences are amplified when DNA containing a particular allele is incubated with its allele-specific oligonucleotide primer and a common primer. The method is simple, reliable, and nonisotopic and obviates the need for digestion with restriction endonucleases or for hybridization with allele-specific oligonucleotide probes. Genotyping DNA by this method overcomes the problem of post-translational modification of the apo E phenotype encountered with isoelectric focusing of the mature plasma apo E protein.
Mathematical model for comparing proficiency testing results across analytical methods
Authors: AuBuchon James P
Published: January 2020

Proficiency testing (PT) programs may fail to establish a range of acceptable performance in a challenge when an insufficient number of participants use a particular method. In this study I analyzed a mathematical approach to establish acceptable performance in alanine aminotransferase (ALT; EC 2.6.1.2) PT challenges. This approach was derived from the mathematical model used in establishing a nationwide ALT standardization system for blood-collection facilities in 1988. A ratio of results was derived between each method in the PT program and an arbitrarily chosen "standard" method. The intent of this approach was to transform a target value for a challenge as determined in the "standard" method to units applicable to methods utilized less often. However, the high degree of variability over time in the ratios for some methods precluded general application of this approach. Therefore, although this simple mathematical method was successful in implementing an ALT standardization system across different methods, a derivation of this approach did not afford comparison of results in PT challenges.
Increased thrombomodulin values in plasma of diabetic men with microangiopathy
Authors: Tanaka Aklra , Ishii Hldenmi , Hiraishi Sayurl , Kazama Mutsuyoshi , Maezawa Hldenor
Published: January 2020

To study the significance of plasma thrombomodulin (TM) values in diabetes mellitus, we determined plasma TM in 34 patients with non-insulin-dependent diabetes mellitus (NIDDM) men, mean age 54 (SE 2) years. Plasma TM was determined by an enzyme immunoassay with anti-TM monoclonal antibodies. The plasma TM values were significantly greater in NIDDM patients with nephropathy than in patients without nephropathy (P less than 0.001). Also, a significant positive correlation was noted between the concentration of plasma TM and serum creatinine (r = 0.55, P less than 0.001). The plasma TM values of the patients with retinopathy were significantly greater than the values of those without it (P less than 0.002). Furthermore, we noted a significant positive correlation (r = 0.78, P less than 0.001) between plasma TM and the severity of diabetic retinopathy as graded by Scott's classification. These results suggest a close relationship between TM and diabetic microangiopathy.
Osteocalcin concentrations in plasma prepared with different anticoagulants
Authors: Power Michael J , O'Dwyer Bernadette , Breen Eugene , Fottrell Patrick F
Published: January 2020

We investigated the effects on plasma osteocalcin concentrations of different anticoagulants used to collect the blood samples. Plasma osteocalcin concentrations measured by enzyme immunoassay and radioimmunoassay are influenced by the nature of the anticoagulants used. The most significant difference between concentrations found in plasma and serum was seen with oxalate/fluoride anticoagulant, which reduced osteocalcin concentrations to 37.3% of serum values. This is probably related to increased hemolysis with this anticoagulant compared with osteocalcin concentrations in plasma prepared with other anticoagulants. Samples prepared with sodium citrate (0.105 mol/L) or lithium heparin gave values 92.4% and 83.6% of those obtained with matched serum samples. Osteocalcin concentrations were relatively stable in plasma and serum at -20 degrees C for two freeze/thaw cycles. In blood from 100 patients there was a good correlation between osteocalcin concentrations in serum and plasma (lithium heparin) (r2 = 0.831); the slope and intercept (+/- SE) were 0.924 +/- 0.04 and 4.92 +/- 1.25 micrograms/L, respectively. However, in 10 patients, serum osteocalcin concentrations were two- to threefold higher than those in matched plasma samples.
Abnormal concentrations of CII, CIII, and E apolipoproteins among apolipoprotein B-containing, B-free, and A-I-containing lipoprotein particles in hemodialysis patients
Authors: Alsayed Naji , Rebourcet RegIs
Published: January 2020

Serum concentrations of total cholesterol, triglycerides, and apolipoproteins (apo) A-I, B, CII, CIII, and E in 36 hemodialysis patients and nine anephric patients were compared with the concentrations in 34 normolipidemic subjects. The dialysis patients displayed a moderate hypertriglyceridemia (1.94 +/- 0.12 vs 1.09 +/- 0.11 mmol/L in controls, mean +/- SEM; P less than 0.001), apo CIII concentrations were also increased (130.2 +/- 2.1 vs 108.4 +/- 0.7 mg/L; P less than 0.001), whereas apo CII (34.5 +/- 0.5 vs 36 +/- 0.5 mg/L; P less than 0.05), apo E (22.7 +/- 0.3 vs 27.9 +/- 0.2 mg/L; P less than 0.001), and apo A-I (1.18 +/- 0.05 vs 1.31 +/- 0.04 g/L; P less than 0.05) were decreased. Concentrations of serum apo B were normal (0.86 +/- 0.03 vs 0.97 +/- 0.07 g/L). In the hemodialysis patients, apo CIII concentrations were increased in apo B-containing lipoproteins (30.1 +/- 0.5 vs 25.0 +/- 0.1 mg/L; P less than 0.001), whereas CII and E were decreased below control values (14.4 +/- 0.2 vs 16.8 +/- 0.1, and 8.2 +/- 0.2 vs 11.4 +/- 0.1 mg/L, respectively; P less than 0.001 each). By calculation, non-B-containing lipoproteins in the hemodialysis group had increased concentrations of apo CIII (100.1 +/- 2.1 vs 83.3 +/- 0.7 mg/L; P less than 0.001) and decreased amounts of apo E (14.5 +/- 0.4 vs 16.4 +/- 0.3 mg/L; P less than 0.001); apo CII content was unchanged (20.1 +/- 0.5 vs 19.3 +/- 0.5 mg/L). Results for apo CII, CIII, and E among apo A-I-containing lipoproteins in both normolipidemic and hemodialysis groups were similar to those in non-B-containing lipoproteins. Finally, the sole significant (P less than 0.01) difference between the anephric and hemodialysis groups was the lower apo E concentrations in the former group. Accumulation of triglyceride-rich lipoproteins in hemodialysis patients may thus be related to the enrichment of apo CIII in apo B-containing lipoproteins and to a marked decrease in the apo CII and E contents.
Determination of cyclosporine by a competitive binding assay with cyclophilin
Authors: Steiner G , Küllinger B , Mayer G , Jie Y , Leibl H , Kovarik J , Woloszczuk W
Published: January 2020

A competitive protein-binding assay for cyclosporine based on use of the intracellular cyclosporine-binding protein cyclophilin (CYP) was used to measure cyclosporin A (CsA) and its bioactive metabolites in whole blood. CYP from cytoplasmic extracts or erythrocyte lysates was applied in the binding assay with use of [3H]CsA as tracer and charcoal adsorption for separating bound from free tracer. Binding affinities of various CsA analogs and metabolites correlated well with their reported in vitro immunosuppressive activities. The assay detected as little CsA as 50 micrograms/L (1 g = 0.832 mmol of CsA), analytical recovery was greater than 80%, and CVs were less than 8% for intra-assay and less than 11% for interassay precision in the range of 150-1000 micrograms/L. We used this assay to measure CsA concentrations in blood and compared the results with those measured by HPLC or by CsA-specific (monoclonal) and CsA-nonspecific (polyclonal) radioimmunoassays. Binding assay results were, in nearly all cases, less than those measured by the nonspecific RIA and frequently greater than 20% above the values determined by the CsA-specific assays. Individual patients had pronounced differences in the relative proportions of CsA, CYP-binding (bioactive) metabolites, and cross-reacting CsA metabolites. Because the presence of bioactive metabolites may considerably contribute to the immunosuppressive activity of CsA, we consider the binding assay clinically useful for measuring CsA in biological fluids.
Interpretations of five monoclonal immunoassays of lutropin and follitropin: effects of normalization with WHO standard
Authors: Vermes I , Bonte H A , v d Sluijs Veer G , Schoemaker J
Published: January 2020

Five mono(oligo)clonal immunometric assays for lutropin (LH) and follitropin (FSH)--bioMérieux, IRE-Medgenix, Serono Diagnostics, Diagnostics Products Corp. (DPC), and LKB--were evaluated in comparison with two polyclonal RIAs (DPC and Amersham). Detection limits varied from 0.04 to 0.32 int. unit/L and 0.06 to 0.86 int. unit/L for LH and FSH, respectively. Intra- and interassay precision (CV) at three concentrations varied from 2.0% to 29.8%, showing that not all kits tested gave acceptable results, especially for LH. Linearity and parallelism were acceptable, except for the DPC FSH kit and the bioMérieux LH kit. High-dose "hook" effects were seen in some kits at LH concentrations of 250 int. units/L, but not in the FSH kits up to concentrations of 350 int. units/L. Reagents in some kits cross-reacted with choriogonadotropin. The clinical validity of the assays was tested in 25 pre- and 25 postmenopausal healthy women and in 66 patients with polycystic ovary disease. In contrast to FSH, LH values varied significantly not only between polyclonal and monoclonal assays but also between the various monoclonal assays, despite the fact that all manufacturers state that their kits are calibrated on the same standards: WHO International Reference Preparation (IRP) 68/40 for LH and 78/549 for FSH. We normalized the results by using new WHO standards: IRP 80/552 for LH and IRP 83/575 for FSH. This decreased significantly the between-kit differences in LH results for individuals. The much-used LH/FSH ratio greater than 3 for diagnosing patients with polycystic ovary disease is not valid when monoclonal assays are used, and is kit-dependent. However, using the normalized results yields a "new" LH/FSH ratio, which is kit-independent and differs significantly between patients and healthy subjects.
Direct calibration for determining aluminum in bone and soft tissues by graphite furnace atomic absorption spectrometry
Authors: Liang Lian , D'Haese Patrick C , Lamberts Ludwig V , De Broe Marc E
Published: January 2020

We describe a direct-calibration method for determining aluminum in bone and soft tissues by graphite furnace atomic absorption spectrometry. Aluminum in bone was determined in uncoated tubes, whereas the analytical performance in soft tissue analysis was markedly improved by using pyrolytically coated tubes with a L'vov platform and added calcium. The analytical imprecision (CV) was less than or equal to 5.4% for aluminium concentrations between 12 and 98 micrograms/L, and analytical recoveries of added analyte varied between 94.5% and 103.0%. Detection limits (2 SD of determinations of the zero standard) were 7 and 6 pg for bone and soft tissues, respectively. Characteristic masses (amounts of Al yielding an absorbance signal of 0.0044 A) were 9 and 8 pg, respectively.
Particle-enhanced turbidimetric immunoassay of sex-hormone-binding globulin in serum
Authors: Deleo D T , Lee I R , Wetherall J D , Newman D J , Medcalf E A , Price C P
Published: January 2020

A particle-enhanced turbidimetric immunoassay (PETIA) for human sex-hormone-binding globulin (SHBG) is described. The method involves use of antibody covalently coupled to latex particles and is almost fully automated, with sample processing being complete in less than 20 min. The working reagents are stable for at least three months, and full calibration of the assay each day is not essential. A particular advantage is that pretreatment of samples is rarely required because the working range of the assay is from 2.0 to 320 nmol/L for nondiluted serum. Intra- and interassay CVs were less than 4.5% and 8.5%, respectively, and mean analytical recovery was 101.5%. SHBG concentrations of 129 serum samples determined by this method and by a commercially available immunoradiometric assay correlated highly.
Evaluation of the fiber-optic antibody-based fluoroimmunosensor for DNA adducts in human placenta samples
Authors: Vo-Dinh T , Alarie J P , Johnson R W , Sepaniak M J , Santella R M
Published: January 2020

This paper presents the application of a fiber-optic antibody-based fluoroimmunosensor (FIS) for measuring DNA adducts of benzo[alpha]pyrene in human placenta samples. The FIS combines the excellent specificity of the antigen-antibody reaction, the high sensitivity of laser excitation, and the versatility of fiber-optic technology. The FIS was used to detect benzo[alpha]pyrene tetrol (BPT) after release from DNA by mild acid hydrolysis. These placenta samples contained one molecule of adduct per 10(7) base pairs. The limit of detection of the FIS for BPT is about 14 amol (14 x 10(-18) mol).