bluuebunny/crossref_metadata_2025_split huggingface dataset:
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

Abstract
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 &lt; 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

Abstract
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 &lt; 0.001), 2-week (r = 0.70, P &lt; 0.001), 3-week (r = 0.72, P &lt; 0.001), and 6-week (r = 0.83, P &lt; 0.001) mean glucose concentrations. GPP correlated significantly with measured glycated albumin determined by boronate affinity columns (r = 0.83, P &lt; .001) and correlated best with the 1-week (r = 0.66, P &lt; 0.001), 2-week (r = 0.64, P &lt; .001) and 3-week (r = 0.60, P &lt; 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

Abstract
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.
ELISA-type titertray assay of IgM anti-GM1 autoantibodies
Authors: Bech E , Jakobsen J , Orntoft T F 
Published: January 2020

Abstract
We report an ELISA-type titertray assay for autoantibodies against the ganglioside GM1. Trays were coated with ganglioside GM1 and reacted with patients' sera; bound IgM was detected with rabbit antibody to human IgM. High-titer serum from a patient was used as calibrator, another patient's serum as the positive control, and the GM1-specific cholera toxin as the control for GM1 coating. Regression curves of serum titers obtained from different patients were linear and parallel. Intra- and interassay CVs were 4.0-7.8% and 5.5-16%, respectively. We detected antibodies at a titer of 1:250 in normal subjects. Analytical specificity of the calibrator serum against GM1 was demonstrated by immune thin-layer chromatography. Anti-GM1 antibodies were increased in patients with chronic inflammatory demyelinating polyradiculoneuropathy (P &lt; 0.002) or multiple sclerosis (P &lt; 0.01). In Guillain-Barré syndrome, preliminary longitudinal studies showed a decrease in anti-GM1 titer that was related to clinical recovery.
Technical and scientific developments in exposure marker methodology
Authors: Sampson E J , Needham L L , Pirkle J L , Hannon W H , Miller D T , Patterson D G , Bernert J T , Ashley D L , Hill R H , Gunter E W 
Published: January 2020

Abstract
Recent advances in techniques to measure markers of exposure to environmental toxicants in humans are changing the ways in which environmental scientists, epidemiologists, and policymakers characterize and interpret such exposure. In this article we review some major technical and scientific developments in exposure marker methodology for estimating internal dose, with special reference to studies conducted at the US Centers for Disease Control and Prevention. We consider important characteristics of laboratory methods, advances in laboratory technology, analytical standards, and quality assurance of laboratory measurements; comparisons with indirect methods for estimating exposures, such as exposure indices and questionnaires; human pharmacokinetic data; sampling problems; surveillance of human exposures to toxicants; and interpretation of measurements. With a view to increasing the reliability of exposure assessment, we make recommendations for obtaining more data on human exposure to toxicants.
Carcinogen adducts: use in diagnosis and risk assessment
Authors: Farmer P B 
Published: January 2020

Abstract
Exposure to genotoxic carcinogens results in the formation of covalently bound adducts of the carcinogens with cellular nucleophilic molecules, including DNA and protein. Quantitative measurements of these adducts may be used to monitor exposure to these carcinogens. The analytical methods required to detect the adducts need to be of exceptional sensitivity and include 32P-postlabeling, immunoassay, and physicochemical techniques (e.g., mass spectrometry or fluorescence measurements). Owing to its accessibility and long lifetime, hemoglobin is also suitable for carcinogen adduct measurement, and techniques based on gas chromatography-mass spectrometry or immunoassay have been developed for this purpose. Although the measurement of adducts is now accepted as a valid means of monitoring exposure to carcinogens, the value of such measurements in indicating carcinogenic risk in humans is less certain. However, adduct concentrations, particularly at low doses of carcinogen, have in several instances been shown to correlate with tumorigenicity in animal experiments.
Complex exposures: potentials for assessing integrated exposures
Authors: Ikeda M 
Published: January 2020

Abstract
To determine empirically the most probable mode of interaction of chemicals given in combination, major occupational health, environmental health, and toxicology journals published in the past 10 years were sorted by eye for studies on noncarcinogenic and nonteratogenic effects of industrial and environmental chemicals in combination. Of the 159 relevant studies, 49 reported "more than additive" effects; however, most of these had methodological weakness in extrapolating the observation to effects in humans; e.g., the dose used was much larger than expected exposure levels in real life. After excluding the studies that were based on unrealistic conditions, the "more than additive" effect was observed in &lt; 5% of the studies reviewed. In the absence of information to suggest otherwise, therefore, the risk of underestimating toxicity by assuming the additiveness is probably &lt; 5%.
Direct stopped-flow fluorescence polarization immunoassay of abused drugs and their metabolites in urine
Authors: Pérez-Bendito D , Gómez-Hens A , Gaikwad A 
Published: January 2020

Abstract
Kinetic methodology was applied to the direct determination of abused drugs (amphetamines, cocaine, and cannabinoids) in urine by stopped-flow fluorescence polarization immunoassay (SF-FPIA). This technique provides analytical data within a few seconds by measuring the variation of polarized fluorescence with time during development of immunochemical reactions. Methods based on this principle are particularly suitable for routine screening of these drugs in urine, being more expeditious than conventional FPIA methods. The dynamic ranges of the calibration curves were 20-300 micrograms/L for d,l-amphetamine, 15-300 micrograms/L for benzoylecgonine (a cocaine metabolite), and 10-400 micrograms/L for 11-nor-delta 8-tetrahydrocannabinol-9-carboxylic acid (a cannabinoid metabolite). The detection limits and within- and between-assay precision were better than those provided by conventional FPIA. Analytical recoveries ranged between 97.5% for d,l-amphetamine and 102.4% for the cannabinoid metabolite. The results for the three analytes were consistent with those obtained by conventional FPIA.
Candidate reference method for determining serum theophylline applied to target-setting in external quality assessment and routine method evaluation
Authors: Thienpont L M , Van Nieuwenhove B , Stöckl D , De Leenheer A P 
Published: January 2020

Abstract
We present a candidate reference method for the determination of serum theophylline by isotope dilution gas chromatography-mass spectrometry, using extractive alkylation in sample preparation. The maximum method bias was &lt; 1.0%. The mean method imprecision (CV) was 0.63% (range 0.37-0.96%), calculated from the results of six measurements independently performed on 3 days. The maximum total error of the method, including the method bias and 95% confidence interval, was &lt; 2.1%. Investigation of various substances and metabolites for interference proved the specificity of the proposed method. The method was used to evaluate three routine assays by linear regression analysis. Performance of the TDx II (Abbott) was excellent and of the Emit 2000 (Syva) assay was good. The Kodak Ektachem assay showed a high dispersion of results and a pronounced positive bias in the subtherapeutic range.
Findings of an external quality assessment scheme for determining aluminum in dialysis fluids and water
Authors: Taylor A , Briggs R J , Cevik C 
Published: January 2020

Abstract
The analytical performance of laboratories participating in the dialysis fluids and water aluminum program of the Guildford External Quality Assessment Scheme over the period 1986-1993 has been reviewed. For aluminum concentrations &gt; 3.33 mumol/L in dialysis fluids, the between-laboratory CV has fallen from approximately 36% to 23%, whereas for specimens of water the reduction was from 36% to approximately 18%. Improvements at lower concentrations were less impressive. Performance of individual participants varied; only a few consistently provided accurate results. Many of the participants are able to measure serum aluminum well, so lack of expertise is not responsible for poor results. We suggest that matrix effects associated with different specimen types have a significant influence on performance and that due account is not always taken of these factors. Resolution of these problems would be aided by appropriate reference materials.
Carboxyhemoglobin determined in neonatal blood with a CO-oximeter unaffected by fetal oxyhemoglobin
Authors: Vreman H J , Stevenson D K 
Published: January 2020

Abstract
Measurements of carboxyhemoglobin (COHb) for clinical purposes are routinely made with CO-oximeters. However, fetal hemoglobin (HbF) interferes with this spectrophotometric method. The manufacturer (Ciba Corning Diagnostics) of a new CO-oximeter (CCD 270) claims that COHb measurements with this instrument are insignificantly affected by HbF. We examined this claim through CO-oximeter analysis of cord blood/adult blood mixtures and compared the results with those obtained by gas chromatography (GC). We also studied the influence of oxygen and bilirubin concentrations. Measurements of COHb with CCD 270 were significantly lower than the GC measurements, but the differences were not clinically important. Linear regression analysis of HbF and COHb measurements (n = 68) showed significant correlation (P &lt; 0.0001) between the two factors for the older CCD 2500 CO-oximeter (R2 = 0.56), but not for the CCD 270 (R2 = 0.06) or GC (R2 = 0.02). Bilirubin concentrations, which affected COHb measurements with CCD 2500, did not significantly affect CCD 270 measurements. We conclude that COHb measurements with CCD 270 CO-oximeter are not affected by HbF or bilirubin concentrations.
Circadian rhythmic variations in serum concentrations of clinically important lipids
Authors: Rivera-Coll A , Fuentes-Arderiu X , Díez-Noguera A 
Published: January 2020

Abstract
Twenty-five apparently healthy adults (13 men and 12 women), mean age 29.5 years (SD 3.6 years), served as subjects in a 24-h study conducted in Barcelona (Spain) in spring of 1990. Six blood samples were collected from each subject at 4-h intervals over a 24-h period, beginning at 1000. The oral temperature was measured at 2-h intervals to facilitate an independent biological time reference. The serum concentrations of apolipoprotein (apo) A-I, apo B, cholesterol, high- and low-density lipoprotein cholesterol, and triglyceride were measured. The circadian rhythms of these quantities were studied with use of a periodic function resulting from the sum of two cosine functions of 24 and 12 h. For serum concentrations of apo A-I and apo B, only the 24- or 12-h components, respectively, were significant. However, the other quantities studied were significantly affected by both rhythmic components. The maximum daily rhythmic variation ranged from 5% (with respect to the daily mean) for apo A-I to 63% for triglyceride concentration. In all cases except triglyceride, the daily maximum values were measured in the afternoon samples, near the time of maximum oral temperature.
Structural and functional assessment of high-density lipoprotein heterogeneity
Authors: Dobiásová M , Frohlich J J 
Published: January 2020

Abstract
We studied the heterogeneity of high-density lipoproteins (HDL) in plasma of 110 subjects, using three different methods: (a) gradient gel electrophoresis (GGE); (b) electroimmunoassay, to measure the concentration of lipoprotein particles containing apoprotein (apo) AI but no apo-AII (LP AI); and (c) cholesterol esterification rate (FERHDL) in very-low- and low-density lipoprotein-depleted plasma. There were two study groups: patients with hypertension, whose plasma lipid profile was similar to their respective controls, and patients with hypoalphalipoproteinemia (hypoalpha), whose family members served as controls. Values for FERHDL were significantly higher in both risk groups than in their respective controls. LP AI was significantly decreased only in the hypoalpha subjects. Generally, LP AI and FERHDL were inversely related. LP AI correlated strongly with plasma HDL-cholesterol, apo AI, and LP AI/AII; FERHDL correlated with those values inversely. LP AI, but not FERHDL, correlated with HDL free cholesterol. On the other hand, FERHDL correlated strongly with plasma concentrations of triglycerides and with the plasma ratio of total/HDL-cholesterol while LP AI did not. GGE determination of the composition of HDL subspecies showed that both FERHDL and LP AI were significantly related to the content of HDL2b particles: FERHDL inversely, LP AI directly; the relative amount of HDL3b,c particles correlated only with FERHDL. We conclude that GGE and FERHDL can be used to quantify both the apparently protective (HDL2b) and risk-associated (HDL3b,c) particles, whereas the concentration of LP AI in plasma mainly reflects the concentration of the HDL2 subpopulation.
Plasma lipoprotein profiles of normocholesterolemic and hypercholesterolemic homozygotes for apolipoprotein E2(Arg158--&gt;Cys) compared
Authors: Zhao S P , Smelt A H , Van den Maagdenberg A M , Van Tol A , Vroom T F , Gevers Leuven J A , Van der Laarse A , Van 't Hooft F M 
Published: January 2020

Abstract
We compared plasma lipoprotein profiles of 15 individuals with normocholesterolemic (plasma cholesterol 4.81 +/- 0.90 mmol/L) familial dysbetalipoproteinemia (NFD) and 15 patients with hypercholesterolemic (plasma cholesterol 10.61 +/- 2.32 mmol/L) familial dysbetalipoproteinemia (HFD), matched for age and sex. All subjects were homozygous for apoE2(Arg158--&gt;Cys). Compared with 15 normolipidemic controls (plasma cholesterol 5.47 +/- 0.92 mmol/L), subjects with NFD and HFD had greater cholesterol concentrations of large very-low-density lipoprotein (VLDL1), small VLDL (VLDL2), and intermediate-density lipoprotein, each of which was correlated to their plasma total cholesterol concentration. VLDL1 and VLDL2 subfractions were enriched in cholesteryl ester, and plasma cholesteryl ester transfer protein activities were increased in both NFD and HFD; however, absolute changes were larger in HFD than in NFD. Concentrations of low-density lipoprotein cholesterol were lower in HFD (1.89 +/- 0.48 mmol/L) and NFD (1.56 +/- 0.36 mmol/L) than in normolipidemic controls (3.35 +/- 0.73 mmol/L). We conclude that all subjects homozygous for apoE2(Arg158--&gt;Cys) show features of dysbetalipoproteinemia.
Premature termination mutations in two patients with deficiency of lactate dehydrogenase H(B) subunit
Authors: Sudo K , Maekawa M , Kanno T , Li S S , Akizuki S , Magara T 
Published: January 2020

Abstract
Two patients with low lactate dehydrogenase (LD) activity were discovered during healthcare examinations and were found to be homozygous for LD-H (heart) subunit deficiency by electrophoretic isoenzyme analysis of serum and erythrocyte hemolysate. The molecular nature of the genetic mutations was characterized by amplification by the polymerase chain reaction and DNA sequencing. In one case, a single-base substitution (T--&gt;G transversion) at codon 147 of the LD-H(B) gene resulted in a nonsense mutation; in the other case, a deletion of 2 base pairs had occurred at codon 139, resulting in a frameshift translation and premature termination.
Endotoxin binding to platelets in blood from patients with a sepsis syndrome
Authors: Salden H J , Bas B M 
Published: January 2020

Abstract
Endotoxin, the lipopolysaccharide cell wall constituent of Gram-negative bacteria, produces symptoms of the Gram-negative sepsis syndrome. By measuring endotoxin in blood from septic patients it may be possible to select a subpopulation of patients in which mortality can be prevented by treatment with anti-endotoxin antibodies. We evaluated the performance of an endotoxin-free blood-collection tube. Within-run and between-run CVs of our endotoxin assay were 4-18% and 8-20%, respectively. In endotoxin-positive samples (LPS &gt; or = 6 ng/L), the concentration of endotoxin in platelet-rich plasma was significantly higher (P &lt; 0.001) than in platelet-poor plasma. Apparent binding of endotoxin to platelets ranged from 0% to 92%. The correlation between the apparent percentage binding of LPS to platelets and the platelet count in platelet-rich plasma is linear and positive, but LPS is not bound solely to platelets. We conclude that endotoxin must be measured in platelet-rich plasma.
Data utilization, not data acquisition, is the main problem
Authors: Altshuler C H 
Published: January 2020

Abstract
Previous studies focusing on the value of laboratory testing have sometimes been flawed because they had not always determined whether the data generated had been appropriately used by clinicians. It has been well documented that neither clinicians nor administrators always use objective data effectively. When data are not used appropriately by clinicians, not only are morbidity and mortality increased, but also care costs are higher. Failures by administrators result in lost opportunities to identify and correct system deficiencies. To provide information support to assure good data utilization, a prototype desktop workstation has been developed and partially implemented. Experience with such a system suggests that not only may it help provide better care more economically, but it can also aid in implementation of Practice Guidelines (Agency for Health Care Policy and Research) and Clinical Indicator (Joint Commission on Accreditation of Healthcare Organizations) programs. Laboratorians can be influential in this effort and promote the use of new knowledge in patient care in a timely and responsible manner.
Cost-effectiveness analysis for evaluation of screening programs: hereditary hemochromatosis
Authors: Buffone G J , Beck J R 
Published: January 2020

Abstract
A significant body of research over the last 10-20 years supports the hypothesis that screening for hereditary hemochromatosis (HH) may be cost-effective, given the low-cost, low-risk therapeutic options available for most homozygous individuals. The factors that confound a straightforward test of this hypothesis include the fact that the disease is not fully penetrant and that, to achieve the anticipated life-year gains, therapy must be instituted before disease complications become irreversible. Recent articles and editorials, as well as practice guidelines prepared by the College of American Pathologists, recommend screening for HH with transferrin saturation and ferritin testing, and with percutaneous liver biopsy for those with positive laboratory test results. Patients at risk would be treated with phlebotomy for life and monitored with ferritin testing. We present a cost-effectiveness analysis that evaluates the efficacy of using a screening strategy to accomplish the desired healthcare goals.
Laboratory diagnostics in light of massive changes in official health policies
Authors: Müller B 
Published: January 2020

Abstract
Virtually 100% of the German population has health insurance. Of this 100%, approximately 90% are members of the Statutory Health Insurance plan. This insurance plan assumes responsibility for practically all of the costs of treatment; self-participation by the patient in the costs is minimal. To counteract the financial deficits of the Statutory Health Insurance funds, the Health Care Reform Act was introduced in 1993, bringing with it massive economy measures for everyone involved in the health sector. For the practitioner sector, this new legislation provides for, among other things, revision of the structure and the reimbursement of laboratories. In this context, the originally agreed-upon introduction of lump-sum payments as reimbursement for laboratory tests was abandoned, in the face of vigorous resistance by the medical profession. Instead, the system of reimbursement for each individual test continues to apply. However, the number of tests is to be limited for each specific group of doctors. In addition, the laboratory fee in the practitioner sector is being reduced by 20%.