bluuebunny/crossref_metadata_2025_split huggingface dataset:
Intracellular magnesium content of mononuclear blood cells and granulocytes isolated from leukemic, infected, and granulocyte colony-stimulating factor-treated patients
Authors: Loun B , Astles R , Copeland K R , Sedor F A 
Published: January 2020

Abstract
The intracellular magnesium (Mg) concentration of granulocytes and mononuclear blood cells (MBCs) was determined in cells isolated from patients with several disorders. The mean (+/-SD) Mg content of MBCs isolated from patients diagnosed with lymphocytic leukemia, myelocytic leukemia, or infection; from patients treated with granulocyte colony-stimulating factor (G-CSF); and from healthy volunteers (control group) was 2.3 (+/-0.6), 3.3 (+/-0.5), 4.1 (+/-0.8), 3.9 (+/-0.4), and 3.9 (+/-0.6) fmol/cell, respectively. The Mg content of MBCs isolated from patients with lymphocytic and myelocytic leukemia, but not those from patients with infection or receiving G-CSF treatment, were significantly lower (P &lt; 0.001) than those from the control subjects. The mean Mg concentration of granulocytes obtained from lymphocytic leukemia, myelocytic leukemia, infection, and G-CSF patients and from the control group was 3.2 (+/-0.9), 3.4 (+/-0.5), 3.8 (+/-0.6), 4.5 (+/-0.6), and 4.6 (+/-0.6) fmol/cell, respectively. Granulocytes isolated from leukemic and infectious patients yielded lower intracellular Mg concentrations (P &lt; 0.005) than those from patients receiving G-CSF and the control group. This study demonstrates that intracellular Mg content is altered in several pathological states. Several factors, including depleted Mg stores or altered intracellular Mg binding sites, could be responsible for these changes. Apparently, intracellular Mg content may be of use in assessing total body Mg status.
Cholinesterase inhibition: complexities in interpretation
Authors: Lotti M 
Published: January 2020

Abstract
Cholinesterases are measured to assess exposures to or effects of organophosphorus esters and carbamates. Plasma butyrylcholinesterase is usually most sensitive to inhibitors, but it has no known physiological function(s); its inhibition reflects exposure. The physiological function of erythrocyte acetylcholinesterase (AChE) also is not known, but the enzyme is the same as that involved in synaptic transmission and its measurement is used to mirror effects on the nervous system. Erythrocyte AChE has large inter- and intraindividual variation, and small changes are detectable by comparison with preexposure values. The relation between inhibition of erythrocytes and nervous tissue AChE depends on the pharmacokinetics of inhibitors. Usually, erythrocyte AChE inhibition overestimates that in the nervous system. Pharmacodynamic factors such as spontaneous reactivation and aging of inhibited enzyme should also be considered in assessing AChE inhibition. Other factors, such as timing of measurement, add complexity because erythrocyte AChE inhibition persists longer than that in the nervous tissues. Cholinergic transmission might also be impaired because of direct effects of organophosphorus esters and carbamates on receptors.
Serum oncoproteins in asbestosis patients
Authors: Partanen R , Koskinen H , Oksa P , Hemminki K , Carney W , Smith S , Brandt-Rauf P 
Published: January 2020

Abstract
Using ELISAs, we determined the concentrations of transforming growth factor alpha (TGF-alpha), the extracellular domain of the erbB-2 receptor (erbB-2 ECD), and mutant p53 protein in stored serum samples of asbestosis patients with and without cancer and control subjects (without asbestosis or cancer). The percentage of individuals in these three groups with increased serum concentrations of TGF-alpha, erbB-2 ECD, and mutant p53, respectively, were: asbestosis patients with cancer, 36%, 16%, 19%; asbestosis patients without cancer, 38%, 19%, 6%; control subjects, 0%, 5%, 10%. Although differences in serum positivity for these oncoproteins were apparent among these groups, the differences did not achieve statistical significance (P &gt; 0.05). In several of the cancer cases, increased concentrations of TGF-alpha, erbB-2 ECD, and mutant p53 were also detected in the stored serum samples collected years before the clinical diagnosis of disease.
External quality assessment in clinical neurochemistry: survey of analysis for cerebrospinal fluid (CSF) proteins based on CSF/serum quotients
Authors: Reiber H 
Published: January 2020

Abstract
Participants (230) from Germany and 20 laboratories in 11 European countries took part in a newly designed cerebrospinal fluid (CSF) survey distributed by INSTAND. Conventional proficiency testing for albumin, IgG, IgA, and IgM in CSF and serum, for total protein in CSF, and for oligoclonal IgG in CSF and serum was combined with evaluation and interpretation of CSF/serum quotients in quotient diagrams. The correct detection of a blood-CSF barrier dysfunction and the pattern of intrathecal immunoglobulin synthesis was judged. The accuracy of CSF/serum quotients and their clinically relevant interpretation was given first priority as a new concept in quality assessment. The main result of the surveys was to confirm that CSF/serum quotients of proteins represent method-independent values approaching the quality of reference values. This finding has consequences for internal quality control of CSF analysis and for accreditation bodies. The sensitivity of the methods for quantifying IgA and IgM in CSF and for detecting oligoclonal IgG fractions is discussed.
Simultaneous determination of alcohols and ethylene glycol in serum by packed- or capillary-column gas chromatography
Authors: Livesey J F , Perkins S L , Tokessy N E , Maddock M J 
Published: January 2020

Abstract
We developed a packed-column chromatographic procedure capable of simultaneous quantitation of methanol, ethanol, isopropanol, acetone, and ethylene glycol. This method was then updated to a rapid, sensitive, wide-bore capillary method. The packed-column system uses direct injection of 1 microL of Na2WO4/H2SO4-deproteinized serum onto a 1.8 m x 2 mm (i.d.) column packed with 80/100 HayeSep R. A linear temperature gradient from 90 to 205 degrees C allows complete elution of all components within 20 min; minimum detection limits are 2 mmol/L. The wide-bore capillary method uses 0.1 microL of sample deproteinized by ultrafiltration, injected onto a 30 m x 0.53 mm (i.d.) 3-microns Rtx-200 (Restek) column. Baseline resolution to a minimum detection limit of 0.1 mmol/L of all compounds is achieved in 5 min with a linear temperature gradient from 40 to 250 degrees C and dual internal standards of n-propanol and 1,2-butanediol.
Discordance between results for serum troponin T and troponin I in renal disease
Authors: Bhayana V , Gougoulias T , Cohoe S , Henderson A R 
Published: January 2020

Abstract
Two patients were investigated for unexplained increases in troponin T. In the first patient, who had rhabdomyolysis and acute renal failure, troponin T reached a peak value of 13.50 micrograms/L (67.5-fold the upper reference limit). The second patient had chronic renal failure and the troponin T peak value was 2.85 micrograms/L (14.3-fold the upper reference limit). Clinical investigations indicated no evidence of myocardial damage. Serum or plasma specimens were analyzed for total creatine kinase (CK), CK-2 mass, CK-2 isoform ratio, myoglobin, troponin T, troponin I, and myosin light chains; all except troponin I were at above-normal concentrations. We also investigated six additional renal patients with above-normal troponin T; troponin I was slightly increased in only one of these six patients. Our findings demonstrate discordance between results for troponin T and troponin I in renal patients.
Measurement and physiological significance of lipoprotein and hepatic lipase activities in preheparin plasma
Authors: Watson T D , Tan C E , McConnell M , Clegg S K , Squires L F , Packard C J 
Published: January 2020

Abstract
A radiochemical method for selective measurement of postheparin lipase activities was adapted to analyze lipoprotein lipase and hepatic lipase in preheparin plasma. The assay sensitivity was increased about four-fold by doubling both the volume of plasma used and the volume of lipolytic products taken for liquid scintillation counting, and was further improved by increasing the incubation period by 50% to 90 min. Rabbit antiserum to human hepatic lipase was unsuitable for the selective measurement of lipoprotein lipase because of apparent endogenous lipolytic activity. Preheparin hepatic lipase, however, was sensitive to inactivation by sodium dodecyl sulfate (SDS), the inhibition being greatest (&gt; 90%) for plasma incubated with an equal volume of 40 mmol/L SDS. Intra- and interassay CVs for the two enzymes were 12.5-14.6% and 17.4-19.7%, respectively. In a cross-sectional study of 84 healthy subjects, pre- and postheparin hepatic lipase activities were higher in men than women, were correlated with indices of obesity, and were significantly correlated with one another, which explained the association of the former with plasma concentrations of high-density lipoprotein (HDL), HDL2, and small, dense low-density lipoproteins. There was no significant relationship between pre- and postheparin lipoprotein lipase activities, but the former were correlated with plasma concentrations of free fatty acids (FFA) and very-low-density lipoprotein. Apparently, preheparin activities of hepatic lipase, but not of lipoprotein lipase, may be a useful measure of the physiological function of "whole body" enzyme activity in cross-sectional and metabolic studies, where heparinization is not possible. Preheparin lipoprotein lipase activities, however, may reflect displacement of the enzyme by FFA and subsequent binding to remnants of triglyceride-rich lipoproteins.
Measurement of methemoglobin in neonatal samples containing fetal hemoglobin
Authors: Speakman E D , Boyd J C , Bruns D E 
Published: January 2020

Abstract
Because of the potential for methemoglobinemia during nitric oxide therapy in newborns, methods are needed to accurately quantify methemoglobin (MetHb) in the presence of the high concentrations of fetal hemoglobin (Hb F), bilirubin, and lipids seen in these patients. Spectral differences between fetal and adult Hbs invalidate assumptions of conventional multiwavelength Hb photometry, so we evaluated an "overdetermined" system (Ciba-Corning Model 270), in which absorbances at seven wavelengths are measured to quantify four Hb derivatives. Adult and umbilical cord blood (Hb F 96%) samples were prepared to contain known MetHb fractions. Measured MetHb was linear in cord blood to &gt; or = 15% MetHb. Within-run precision (CV) was &lt; 2.2% (n = 10) at each of seven MetHb fractions between 5% and 100%. Measured (y) and expected (x) MetHb fractions in cord blood were in good agreement (y = 1.0200x + 0.100, Sylx = 0). Added bilibrubin (200 mg/L serum) and lipid (30 g/L) did not interfere. No significant differences were seen for adult and cord blood samples with identical MetHb fractions (P = 0.72), whereas a significant difference was noted with an exactly determined system (P = 0.0033). At clinically relevant MetHb fractions (&lt; 15%), a trend towards increased values in cord blood was noted with an exactly determined system (y = 1.0520x + 0.7600). We conclude that this overdetermined system measures MetHb accurately in samples from patients with large concentrations of Hb F.
Clinical capillary electrophoresis
Authors: Landers J P 
Published: January 2020

Abstract
Capillary electrophoresis is a relatively new analytical technique that has begun to have an impact in the clinical laboratory, both for routine analyses and for those that are more esoteric. Its potential for automated, rapid, high-efficiency separations makes it appealing as a replacement for some of the more labor-intensive assays carried out in electrophoretic gels and as a complement to companion techniques such as HPLC. Among the many attractive characteristics of this technology is its versatility for analyses of a diverse spectrum of analytes, ranging from small organic ions to macromolecular protein complexes or DNA. The focus of this commentary is to familiarize the clinical scientist with the instrumentation and principles of capillary electrophoretic separation and to review the recent research demonstrating the applicability of this technology to the clinical laboratory.
Electrochemical dehydrogenase-based homogeneous assays in whole blood
Authors: Yao H , Halsall H B , Heineman W R , Jenkins S H 
Published: January 2020

Abstract
An electrochemical method has been developed for determining NADH in whole blood for dehydrogenase-based assays by flow-injection analysis. NADH generated by dehydrogenase is oxidized by an electron-transfer coupling reagent, 2,6-dichloroindophenol (DCIP). The reduced form of DCIP (DCIPH2) is measured amperometrically by flow-injection analysis. Endogenous interferents were inhibited by p-hydroxymercuribenzoate. Electrode fouling by proteins was not observed under assay conditions. The Emit theophylline enzyme immunoassay and the hexokinase glucose assay were used as models. For the glucose assay, the intraassay CVs were 15% at 0.31 g/L and 3.5% at 1.82 g/L. Recoveries of glucose from whole blood (compared with that for aqueous standards) were 109%, 97.9%, and 101% at 0.050, 2.00, and 5.00 g/L glucose, respectively, and 104%, 101%, and 102% for theophylline at concentrations of 5.0 (low), 16.4 (medium), and 30.2 (high) mg/L, respectively, with corresponding precisions of 12%, 9.5%, and 8.8%. Both assays correlated well with results by reference methods. These studies demonstrate that this method can measure NADH in whole blood without prior separation and that it is potentially applicable to other dehydrogenase-based assays in whole blood.
Simultaneous assessments of exocrine pancreatic function by cholesteryl-[14C]octanoate breath test and measurement of plasma p-aminobenzoic acid
Authors: Bruno M J , Hoek F J , Delzenne B , van Leeuwen D J , Schteingart C D , Hofmann A F , Tytgat G N 
Published: January 2020

Abstract
Two noninvasive tests for assessing pancreatic exocrine function, the cholesteryl-[14C]octanoate breath test and the HPLCN-benzoyl-tyrosyl-p-aminobenzoic acid/p-aminosalicylic acid (NBT-PABA/PAS) test, were simultaneously performed in nine patients with pancreatic exocrine insufficiency due to chronic pancreatitis and in nine healthy volunteers. 14CO2 output in breath and plasma PABA concentration rose slowly in patients but increased rapidly in healthy subjects. The measurement time giving the best discrimination between both groups was 120 min for the cholesteryl-[14C]octanoate breath test and 90 min for the plasma PABA test. At these points, both single-sample tests had essentially identical diagnostic sensitivity. The diagnostic sensitivities of the two single-sample tests were equal to that of the cumulative 6-h urinary PABA recovery and the cumulative 6-h urinary PABA/PAS ratio. We conclude that, for both the cholesteryl-[14C]octanoate breath test and the plasma PABA test, a single test sample is sufficient for rapid detection of impaired exocrine pancreatic function.
Los Angeles County-University of Southern California Medical Center clinical pathology case conference: extreme hypermagnesemia in a neonate
Authors: Huey C G , Chan K M , Wong E T , Nelson J M , Durand M 
Published: January 2020

Abstract
A preterm male infant born at 33 weeks of gestation developed respiratory depression and apnea at approximately 20 h after birth. Laboratory tests indicated severe hypermagnesemia, acidosis, and hypercalcemia. Cord blood and maternal blood concentrations of magnesium were normal. The effects and possible causes of hypermagnesemia are reviewed. The infant recovered with treatment, although the etiology of his hypermagnesemia remains unknown.
Automated dibucaine number measurement with DuPont Dimension ES and AR analyzers
Authors: Holownia P , Newman D J , Bruno C , LaGamba P , Gerrits M , Salemink G , Ossani M , Price C P 
Published: January 2020

Abstract
We report a fully automated method for determining dibucaine number (DN) in a single-run procedure involving Dimension cholinesterase (CHE) Flex pseudo-(P)CHE reagents. The method was developed and optimized with the "open channels" and "kinetic" software facilities of the Dimension-ES instrument, where the DN is calculated automatically by an algorithm from the ratio of the uninhibited and inhibited rates, measured bichromatically, from a single analysis. The protocol was satisfactorily assessed for substrate depletion, linearity, reagent stability. and the effects of different dibucaine concentrations. Validation was performed across a range of CHE activities (1.5-22 kU/L) representing the three main genotypes, UU, UA, and AA. The respective DNs (mean +/- SD), determined on the Dimension-ES, were 82.0 +/- 1.6 (n = 32), 71.0 +/- 3.1 (n = 10), and 23.0 +/- 2.7 (n = 14), with corresponding imprecisions (CV) of 0.3%, 0.6%, and 5.2% (intraassay) and 0.7%, 0.7%, and 8.6% (interassay). Comparisons with reference (x) laboratory values and the DuPont aca (x') procedure (n = 53) gave regression equations of: y = 0.88x + 11.2, r = 0.99, and y = 0.85x' + 11.9, r = 0.99. A separate trial conducted with a Dimension-AR instrument gave similar performances. We conclude that the new DN method is fast, efficient, and appropriate for clinical use.
Vitamin C and glycohemoglobin
Authors: Weykamp C W , Penders T J , Baadenhuijsen H , Muskiet F A , Martina W , van der Slik W 
Published: January 2020

Abstract
Three groups of 10 age- and sex-matched nondiabetic volunteers took 0, 750, or 1500 mg of vitamin C each day for 12 weeks. Glycohemoglobin (GHb) was measured by HPLC, electrophoresis, affinity chromatography, and immunoassay at baseline (-4 weeks and -1 day), during supplementation (6 weeks and 12 weeks), and after supplementation ended (6 and 12 weeks). Plasma vitamin C increased twofold during supplementation but, in contrast with the results of Davie et al. (Diabetes 1992; 41:167-73), there were no between-group differences in GHb, glucose, and fructosamine concentrations. Fructosamine may have increased with storage time. The net effects of vitamin C on absolute GHb at 12 weeks vs -1 day (and at 12 weeks vs 12 weeks after) in % GHb amounted to: HPLC -0.035 (-0.050); electrophoresis +0.005 (+0.035); affinity chromatography -0.070 (+0.015); and immunoassay -0.110 (+0.025). We conclude that supplementation of nondiabetics with 750 or 1500 mg of vitamin C daily for 12 weeks does not cause interference in GHb determinations by HPLC, electrophoresis, affinity chromatography, or immunoassay, and does not reduce in vivo Hb glycation.
Direct determination of lipoprotein(a) cholesterol by ultracentrifugation and agarose gel electrophoresis with enzymatic staining for cholesterol
Authors: Nauck M , Winkler K , Wittmann C , Mayer H , Luley C , März W , Wieland H 
Published: January 2020

Abstract
Lipoprotein(a) [(Lp(a)], a low-density lipoprotein (LDL)-like particle, contains in addition to LDL a specific protein component, apolipoprotein(a) [apo(a)]. Conventionally, Lp(a) has been measured by immunological methods that distinguish between Lp(a) and LDL by dealing with apo(a) as an antigen. We describe a new method to determine Lp(a) on the basis of its cholesterol content. Very-low-density lipoproteins were removed from serum by preparative ultracentrifugation at a density of 1.006 kg/L. The infranate was subjected to agarose gel electrophoresis to separate Lp(a) and LDL. Lp(a) cholesterol was then determined by direct enzymatic staining for cholesterol. On electrophoresis of the &gt; 1.006 kg/L (bottom) fraction, Lp(a) migrates to the pre-beta position, regardless of the genetic apo(a) isoform. The interassay CVs of Lp(a) cholesterol determinations ranged from 6.9% to 11.5%, and the results correlated well with the Lp(a) concentrations measured by immunonephelometry (r = 0.937). There was an inverse relation between the molecular mass of the genetically determined apo(a) isoforms and Lp(a) cholesterol concentrations. Patients with angiographically proven coronary artery disease (CAD) had significantly more Lp(a) cholesterol than healthy controls did. The ratio of Lp(a) cholesterol to immunologically determined Lp(a) tended to be lower in CAD patients, suggesting that Lp(a) particles contained less cholesterol than apo(a). In addition, the new method allows determination of LDL cholesterol without contamination by Lp(a).
Financial viability of screening for drugs of abuse
Authors: Peat M A 
Published: January 2020

Abstract
Urine drug testing is now a common practice in the American workplace; a recent survey indicated that &gt; 90% of companies with &gt; 5000 employees have some type of testing program. These programs have indeed reduced the rate of drug-positive test results; for example, recent data from the Federal Aviation Agency show that the rate for 1993 was 0.82% compared with 0.95% for 1992. Many corporations have stated that urine drug testing, as a component of a substance abuse policy, results in significant savings, e.g., from decreased absenteeism and turnover. The United States Postal Service recently completed a longitudinal study on the economic benefits and found that, over the average tenure of an annual intake of employees, there were savings of more than $100 million. Although this study clearly demonstrates the financial benefits of preemployment drug testing, the decision to test is not based solely on this but also on the regulatory environment and on the potential impact of a major accident attributable to the use of drugs or alcohol in the workplace.
D-phenylalanyl-L-prolyl-L-arginine chloromethyl ketone (PPACK): alternative anticoagulant to heparin salts for blood gas and electrolyte specimens
Authors: Lyon M E , Fine J S , Henderson P J , Lyon A W 
Published: January 2020

Abstract
D-Phenylalanyl-L-prolyl-L-arginine chloromethyl ketone (PPACK), a selective thrombin inhibitor, was evaluated as an alternative anticoagulant to lithium heparin (LiHep) for blood gas and whole-blood electrolyte analyses. Initial studies in serum revealed a negative proportional bias for ionized calcium (iCa) concentration measured in the range of increasing concentrations of LiHep (-0.02 mmol/L iCa per 33 kIU/L), whereas no bias in iCa concentration was detected with increasing concentrations of PPACK. No anticoagulant-dependent changes in serum sodium, potassium, chloride, glucose, lactate, ionized magnesium, or pH were detected with either PPACK or LiHep. Similarly, no bias was observed in the measurement of whole-blood PO2, PCO2, pH, or sodium or potassium concentrations with either anticoagulant. Whole blood anticoagulated with LiHep (33 kIU/L) demonstrated a consistent -0.06 +/- 0.01 mmol/L bias for iCa compared with a nonanticoagulated whole-blood control. In comparison, no iCa bias was observed with PPACK-anticoagulated whole blood. We conclude that PPACK has ideal bias-free properties as an anticoagulant in analyses for blood gases, electrolytes, and iCa.
Undercarboxylated osteocalcin and development of a method to determine vitamin K status
Authors: Sokoll L J , O'Brien M E , Camilo M E , Sadowski J A 
Published: January 2020

Abstract
We developed a RIA involving a polyclonal antibody against bovine osteocalcin, which has a carboxy-terminal epitope. Although the antibody recognizes both native and descarboxy osteocalcin, the two forms of osteocalcin were differentiated by adsorption to barium sulfate, taking advantage of the calcium-binding properties of the vitamin K-dependent gla domain. To test the clinical application of undercarboxylated osteocalcin, we examined the effect of minidose warfarin on this measure in nine healthy subjects, ages 60 to 80 years. The percentage of undercarboxylated osteocalcin increased by 170% +/- 36% (mean +/- SE) after 7 days of treatment with warfarin, 1 mg/day. The effectiveness of undercarboxylated osteocalcin as a sensitive measure of vitamin K nutritional status was further established when concentrations dropped to 17% +/- 14% below baseline with 2 days of repletion with vitamin K1, 5 mg/day, during which prothrombin times did not leave the normal range.