bluuebunny/crossref_metadata_2025_split huggingface dataset:
Determination of lead in urine and whole blood by stable isotope dilution gas chromatography-mass spectrometry
Authors: Aggarwal S K , Kinter M , Herold D A 
Published: January 2020

Abstract
A stable isotope dilution gas chromatography-mass spectrometry (GC-MS) method is described for the determination of lead (Pb) in urine and whole blood. The use of lithium bis(trifluoroethyl)dithiocarbamate Pb(FDEDTC) as a chelating agent showed strong memory effect, restricting the range of Pb isotope ratios that can be measured in unknown samples. To overcome this carryover problem, we further derivatized the Pb(FDEDTC)2 chelate with 4-fluorophenyl magnesium bromide to form Pb(FC6H4)4. The sequential analyses of solutions of natural Pb and enriched 204Pb with Pb(FC6H4)4 chelate by GC-MS demonstrated no observable memory effect. Precision and accuracy of Pb isotope ratio measurements with Pb(FC6H4)4 were established, and the isotope dilution GC-MS method was validated by determining Pb concentrations in urine standards from the National Institute of Standards and Technology, urine and blood reference materials from the New York State Department of Health, and blood Pb survey samples from the College of American Pathologists.
Mechanism and elimination of aspirin-induced interference in Emit II d.a.u. assays
Authors: Linder M W , Valdes R 
Published: January 2020

Abstract
The presence of salicylates in urine reduces the signal in Emit assays (Syva), potentially yielding false-negative drugs-of-abuse screening results. We demonstrate that the principal urinary metabolite of salicylate, salicyluric acid (SUA; 2-hydroxybenzoylaminoacetic acid), interferes with the measurement of NADH formed in the assay by reducing the molar absorptivity of NADH at 340 nm. Thus, for a given concentration of d.a.u. analyte the change in absorbance over the assay time interval is less in the presence of SUA. With the Emit cocaine assay on the Hitachi 704 analyzer, the rate of absorbance change (delta AR) monitored at 340 nm for a specimen containing approximately 270 micrograms/L benzoylecgonine (BE) was 57 +/- 1.9 mA/min without SUA and 29 +/- 2.7 mA/min with 5 g/L SUA (n = 20). In contrast, delta AR determined at 376 nm was 18.6 +/- 0.5 mA/min with and 17.9 +/- 0.8 mA/min without 5 g/L SUA (n = 20). Measuring the Emit assay signal at wavelengths where SUA has no absorbance (376 nm) eliminates the interference due to SUA while maintaining the precision of the assay near the cutoff concentration for BE (300 micrograms/L).
Familial high serum concentrations of the carboxyl-terminal propeptide of type I procollagen
Authors: Sorva A , Tähtelä R , Risteli J , Risteli L , Laitinen K , Juntunen-Backman K , Sorva R 
Published: January 2020

Abstract
We describe a family with an apparently autosomal-dominant trait that caused extremely high circulating concentrations of the carboxyl-terminal propeptide of type I procollagen (PICP). All family members examined had normal values for other biochemical markers of bone formation and degradation and no related clinical abnormalities. Furthermore, their serum concentrations of the amino-terminal propeptide of type I procollagen (PINP) were normal. Although PINP and PICP are released from the same precursor molecule, PINP is cleared from the circulation via the scavenger receptor in liver endothelial cells, whereas PICP is cleared via the mannose receptor of these cells. We thus hypothesize that the clearance of circulating PICP is compromised in the affected subjects of this family, the result of either a defective mannose receptor function or an abnormal molecular structure of their PICP.
Conceptual framework for evaluating laboratory tests: case-finding in ambulatory patients
Authors: Silverstein M D , Boland B J 
Published: January 2020

Abstract
In response to concerns about inappropriate testing and healthcare costs, clinicians and laboratorians should work together to evaluate laboratory tests. Studies of routine laboratory tests ordered for screening and case-finding in the preoperative setting, at hospital admission, and in the ambulatory setting have not provided sufficient evidence of the benefits of case-finding when evaluated against commonly used criteria for screening procedures. We adapt a conceptual framework developed from radiology for evaluating imaging technologies to evaluate laboratory tests. The framework addresses diagnostic efficacy (whether the test correctly identifies abnormalities), diagnostic effectiveness (whether the test changes the physician's diagnoses), therapeutic efficacy (whether the test changes patient management), and therapeutic effectiveness (whether the test changes patients' outcomes). We propose that clinicians and laboratorians use this framework to evaluate the diagnostic efficacy, diagnostic effectiveness, therapeutic efficacy, and therapeutic effectiveness of laboratory tests in the ambulatory setting and in other settings.
Components of biological variation in prolyl endopeptidase and dipeptidyl-peptidase IV activity in plasma of healthy subjects
Authors: Maes M , Scharpé S , De Meester I , Goossens P , Wauters A , Neels H , Verkerk R , De Meyer F , D'Hondt P , Peeters D 
Published: January 2020

Abstract
We investigated the components of biological variation in plasma prolyl endopeptidase (PEP; EC 3.4.21.26) and dipeptidyl-peptidase IV (DPP IV; EC 3.4..14.5) activity in healthy individuals. We took monthly blood samples from 26 healthy volunteers for determination of plasma PEP and DPP IV activity during one calendar year. The estimated CVs for PEP activity were: total (CVt) = 25.0%, interindividual (CVg) = 13.9%, and intraindividual (CVi) = 16.8%. There was a statistically significant (P &lt; 0.0001) seasonal pattern in plasma PEP activity, with significantly higher values in the fall than in the other seasons. The peak-trough difference in the yearly variation in PEP activity, expressed as a percentage of the mean, was as high as 56.8%. The estimated CVs for DPP IV activity were: CVt = 17.1%, CVg = 14.5%, and CVi = 8.2%. DPP IV activity was significantly (P &lt; 0.0001) higher in summer than in the other seasons but the amplitude of the yearly variation was small.
Microwave-induced rapid preparation of fluoro-derivatives of amphetamine, methamphetamine, and 3,4-methylenedioxymethamphetamine for GC-MS confirmation assays
Authors: Thompson W C , Dasgupta A 
Published: January 2020

Abstract
We prepared trifluoroacetyl, pentafluoropropyl, and heptafluorobutyl derivatives of amphetamine, methamphetamine, and 3,4-methylenedioxymethamphetamine (MDMA) in 45 s, 1 min, and 6 min, respectively, by using microwave irradiation. Conventional techniques require heating the reaction mixture for 15 min at 40 degrees C for trifluoroacetyl derivatives, 15 min at 75 degrees C for pentafluoropropyl derivatives, and 40 min at 60 degrees C for heptafluorobutyl derivatives. The mass-spectral fragmentation patterns and the gas-chromatographic retention times of the derivatives obtained by both microwave irradiation and conventional heating were similar. Perfluorooctanoyl derivatives of amphetamine can be prepared quantitatively by either heating the reaction mixture for 30 min at 60 degrees C or by 1 min of microwave irradiation. Conversion of methamphetamine and MDMA to the corresponding perfluorooctanoyl derivatives was not quantitative by either technique, although the yield of the derivative in the conventional technique was much higher.
Fatty acids in erythrocytes measured by isocratic HPLC
Authors: Abushufa R , Reed P , Weinkove C 
Published: January 2020

Abstract
We developed an isocratic reversed-phase HPLC method to measure arachidonic, palmitoleic, linoleic, eicosatrienoic, oleic, palmitic, and stearic acids from hydrolyzed erythrocytes. Washed erythrocytes were heated in methanol:HCl and the fatty acids extracted into hexane:amyl alcohol. After derivatization with 4-bromomethyl-7-methoxycoumarin, samples diluted in mobile phase (acetonitrile:water, 85:15 by vol) were injected onto a 250 x 4.6 mm C18 column, and the eluted fatty acids were detected fluorometrically. For all analytes, the mean within-batch CV was 8.2% (5.5-10.8%), the mean limit of detection was 7.0 mumol/L, a linear response was maintained up to 400 mumol/L, and results agreed well with those by gas chromatography. The addition of antioxidant (butylated hydroxytoluene) was essential for sample stability. We discuss hydrolysis and extraction times, derivatization temperature, critical steps in chromatography, and concentration units.
High-density lipoprotein subfractions measured in stored serum
Authors: Bausserman L L , Saritelli A L , Milosavljevic D 
Published: January 2020

Abstract
We compared the effects of freezing serum on the determination of high-density lipoprotein (HDL) subfractions by two dual-precipitation methods, heparin and manganese chloride/dextran sulfate (HM/DS) (Gidez et al., J Lipid Res 1982;23:1206-23) and DS/DS (Warnick et al., Clin Chem 1982;28:1574), and by ultracentrifugation. Storing serum for 1 month at -70 degrees C resulted in reduced HDL3-cholesterol by ultracentrifugation and reduced total and HDL3-cholesterol by the DS/DS method. There was no change in either total HDL-cholesterol or HDL3-cholesterol with the HM/DS method. Additional studies involving only HM/DS indicated that total HDL-cholesterol in serum stored at 4 degrees C begins to decline after 3 days (-3.1 +/- 3.5%, P &lt; 0.1). HDL was stable at -20 degrees C for 2 weeks but both total and HDL3-cholesterol decreased significantly after 1 month. Storage of serum at -70 degrees C resulted in no changes for 1 year; however, at 18 months, HDL3-cholesterol was reduced 13% (P = 0.002). We conclude that HDL subfractions can be determined accurately in serum as well as in plasma after storage at -70 degrees C for up to 1 year.
Phospholipase A2, C-reactive protein, and white blood cell count in the diagnosis of acute appendicitis
Authors: Grönroos J M , Forsström J J , Irjala K , Nevalainen T J 
Published: January 2020

Abstract
We compared the predictive value of determining group II phospholipase A2 (PLA2) in serum for diagnosing acute appendicitis with the predictive values of white blood cell count (WBC) and measurement of C-reactive protein (CRP). In this prospective study, we included 186 patients who were undergoing appendectomy after clinical diagnoses of acute appendicitis. The performance of each test was measured by receiver-operating characteristic curves. WBC was the test of choice in diagnosing uncomplicated acute appendicitis. However, in contrast to CRP and PLA2, which increased in patients with protracted inflammation, there was not a concomitant increase in WBC. Therefore, especially CRP, but also PLA2, were better indicators of appendiceal perforation or abscess formation than was WBC. Increased WBC, CRP, and PLA2 values did not unequivocally corroborate the clinical suspicion of appendicitis, but if all three values were within normal limits, acute appendicitis could be excluded with a 100% predictive value. PLA2 values showed a highly significant correlation with CRP but not with WBC values, which supports the view that PLA2 represents an acute-phase reactant.
ELISA of pentosidine, an advanced glycation end product, in biological specimens
Authors: Taneda S , Monnier V M 
Published: January 2020

Abstract
Pentosidine is a fluorescent protein cross-link and glycoxidation marker for the advanced glycation reaction in diabetes, aging, and uremia. We raised polyclonal antibodies in New Zealand White rabbits against this hapten coupled to keyhole limpet hemocyanin. The antibodies detected by ELISA reacted strongly with free pentosidine but not with pentosidine-like compounds. The working range of the competitive ELISA for standard pentosidine was 0.1-100 pmol. Pentosidine was detectable in bovine serum albumin incubated with ribose as a function of incubation time. Immunoblotting studies showed that pentosidine specifically stained in oligomers of lysozyme incubated with ribose. Digestion with protease (Pronase E, 20 g/kg) as well as acid hydrolysis enhanced the immunoreactivity of samples, the pentosidine values in digested human plasma correlating with those measured by HPLC (r = 0.98). Pentosidine in diabetic and uremic plasma digested with Pronase E was significantly higher than normal (P &lt; 0.01; mean +/- SD): 1620 +/- 1940 and 2630 +/- 1320 [corrected] nmol/L, respectively, vs 151 +/- 55 nmol/L (normal). Amounts of pentosidine in hydrolyzed skin collagen increased with age and were increased in diabetes and uremia. This ELISA provides a new tool for assessing the role of the advanced Maillard reaction in aging and age-related diseases.
Nanotechnology: basic concepts and definitions
Authors: Kaehler T 
Published: January 2020

Abstract
Molecular nanotechnology is an engineering discipline in which the goal is to build devices and structures that have every atom in the proper place. By means of this general purpose material-processing technology it will be possible to build almost any rigid, covalently bonded structure. Identical parts will be truly identical, enabling energy conversion and computation systems to have extremely high performance and reliability. Assembly will be done by mechanosynthesis, the process of holding two reactive molecules in contact with each other in a controlled orientation. Synthesis will be done on nanoscale assembly lines called molecular mills, where systems of moving belts will press individual molecules together and catalyze 10(6) reactions/s per station. High-performance mechanical computers will use moving rods to block the motion of other rods. The most important physical limit will be radiation damage. Without redundancy, a subsystem lasting 100 years will be limited to 10(6) nm3.
Kromoscopic analysis: a possible alternative to spectroscopic analysis for noninvasive measurement of analytes in vivo
Authors: Sodickson L A , Block M J 
Published: January 2020

Abstract
Light that penetrates scattering media shows nonlinearities that mask the broad and shallow perturbations made by trace analytes on the background illuminant spectrum. Narrow-band spectroscopic decomposition and deconvolution of such weak bands is a formidable analytical task that pushes the fundamentally linear spectroscopic method beyond practical limits. Kromoscopy is a high-dimensional analog of human color perception; it has broad-band spectrally overlapping detectors similar to those of the visual system, but in the infrared. Analyte bands are integrated fully in two or more detectors with different relative weightings. As in color vision, the analyte information is coded in the direct correlations between detector signals, which individually have higher signal-to-noise ratios than their spectroscopic counterparts. Our Kromoscopic instrument responds directly to glucose in aqueous solution, is not affected by temperature disturbances, and is fast enough to measure physiologically induced Kromoscopic changes in the arterial pulse waveform with high precision.
The white IRIS leukocyte differential analyzer for rapid high-precision differentials based on images of cytoprobe-reacted cells
Authors: Kasdan H L , Pelmulder J P , Spolter L , Levitt G B , Lincir M R , Coward G N , Haiby S I , Lives J , Sun N C , Deindoerfer F H 
Published: January 2020

Abstract
Combining unique cytoprobe, rapid hemacyte fractionation, and novel color image analysis, The White IRIS (TWI) extends automated intelligent microscopy to leukocyte differentiation. TWI provides flow cytometry precision and microscopical resolution to review specimens flagged by hematology analyzers with differential capabilities or to complement other analyzers without these capabilities. The system includes compartments for closed sampling, rapid leukocyte-rich plasma preparation, cytoprobe-induced metachromasia, and collection and color analysis of leukocyte images, and presents the results as a single-view 500-cell differential on a 20-in. (50-cm) touch-screen monitor. Method correlations for the five mature cell types averaging r &gt; 0.90 were obtained with a prototype system. Classification of normal and abnormal specimens showed 95% agreement with a reference method without any undetected significant morphologic abnormality. False-positive and false-negative rates of 7.27% and 3.53%, respectively, exceeded performance of current commercial systems. Case studies demonstrate the ease and speed with which unusual pathologies and leukemias can be observed and interpreted.
D-lactic acidemia and aciduria in pediatric and adult patients with short bowel syndrome
Authors: Bongaerts G , Tolboom J , Naber T , Bakkeren J , Severijnen R , Willems H 
Published: January 2020

Abstract
D-Lactate produced by abundant intestinal lactobacilli during acidotic episodes in short bowel (SB) patients is commonly regarded as a main factor in the pathogenesis of SB syndrome-associated (D-lactic) acidosis. Since we had observed that gram-positive bacteria, mainly lactobacilli, were abundant even in the absence of acidosis, we studied serum concentrations and urinary excretions of D- and L-lactate in young and adult SB patients, especially during nonacidotic periods. Serum L-lactate and urinary L-lactate excretion were similar in adults and children. Serum D-lactate and urinary D-lactate excretion were higher in SB children than in SB adults. Food consumption affects D-lactate production and alters D-lactic acidemia and aciduria. We conclude that D-lactate is frequently present in serum of SB patients even in the absence of acidosis. High serum concentrations and urinary excretions may reflect dietary factors in these patients.
Increased hepatic secretion of very-low-density lipoprotein apolipoprotein B-100 in cholesteryl ester storage disease
Authors: Cummings M H , Watts G F 
Published: January 2020

Abstract
Using a stable isotope method, we measured the hepatic secretion rate of very-low-density lipoprotein apolipoprotein B-100 (VLDL apoB) in a 26-year-old women who had dyslipidemia due to cholesteryl ester storage disease (CESD) and in five normolipidemic subjects. [1-13C]Leucine was administered by a primed constant intravenous infusion and the enrichment of VLDL apoB was determined by gas chromatography-mass spectrometry. The absolute secretion rate (ASR) of VLDL apoB in the patient was more than twice the mean ASR of the normolipidemic group (17.1 vs 8.0 +/- 0.8 mg/kg body wt. per day). The plasma mevalonic acid concentration, a measure of intrahepatic cholesterol synthesis, was also greater in the patient than in the normolipidemic subjects (8.3 vs 4.4 +/- 1.8 micrograms/L). The findings are consistent with the hypothesis that in CESD increased intrahepatic synthesis of cholesterol stimulates hepatic secretion of VLDL apoB and this may partly account for the dyslipidemia.
Enhanced chemiluminescence labeled-antibody immunoassay (Amerlite-MAB) for free thyroxine: design, development, and technical validation
Authors: Christofides N D , Sheehan C P 
Published: January 2020

Abstract
We describe the development and validation of a one-step nonradioactive immunoassay for free thyroxine (Amerlite-MAB FT4) in serum or plasma, in the dedicated Amerlite enhanced luminescence assay system. A monoclonal antibody to thyroxine (T4), conjugated with horseradish peroxidase (HRP; EC 1.11.1.7), competes for binding with FT4 or with a conjugate of a protein and L-triiodothyronine immobilized onto the surface of the assay microwells. The signal is generated by antibody-HRP bound to the protein-T3 conjugate, with luminol as substrate. The assay design exploits the high sensitivity of luminescence signal detection, permitting minimal sample dilution and T4 sampling by the antibody. It withstands progressive dilution of serum and is unaffected by T4-binding proteins in serum. The disclosure and validation of this FT4 assay follows guidelines recommended by the American Thyroid Association.
Structural and functional polymorphism of lipoprotein(a): biological and clinical implications
Authors: Scanu A M 
Published: January 2020

Abstract
Lipoprotein(a) [Lp(a)], a variant of low-density lipoprotein, is heterogeneous in density because of variability in the content and composition of its core lipids and size polymorphism of its specific glycoprotein component, apolipoprotein(a) [apo(a)]. In some individuals, density polymorphism may also derive from the fact that Lp(a) contains 2 mol of apo(a) per mole of apoB100, contrary to the more common 1:1 molar stoichiometry. Moreover, the size of apo(a) is polymorphic because of variations in the number of kringle 4 type 2 repeats. Another type of apo(a) polymorphism is related to sequence mutations at the kringle level. Two mutations can occur in kringle 4 type 10: one, Trp72--&gt;Arg, is affiliated with an Lp(a) that is lysine-binding defective; the other, Met66--&gt;Thr, with a normal lysine-binding function. Thus, Lp(a) is structurally and functionally polymorphic, a notion that must be considered in assessing the cardiovascular pathogenicity of this lipoprotein variant and in immunoquantification assays.
Plasma homocyst(e)ine and arterial occlusive diseases: a mini-review
Authors: Malinow M R 
Published: January 2020

Abstract
Homocysteine (HCY), which is derived from the intracellular metabolism of methionine, is exported into plasma, where it circulates mostly in oxidized forms (i.e., homocystine and cysteine-HCY disulfide) and mainly bound to proteins. Concentrations of total HCY, or homocyst(e)ine [H(e)], are increased in 15-40% of patients with coronary, cerebral, or peripheral arterial diseases. Such association of H(e) with arterial occlusive diseases has been documented in retrospective, cross-sectional, and prospective studies. Concentrations of H(e) are also increased in subjects having thickened carotid arteries, as determined by ultrasonography, and who are asymptomatic for atherosclerosis. Statistical analyses of data from several series of patients demonstrate that H(e) concentrations are associated with coronary artery disease, independently from most other risk factors for atherosclerosis. The increased concentrations of H(e) are readily corrected by folic acid, occasionally supplemented with pyridoxine, vitamin B12, choline, or betaine. Whether these supplements affect the evolution of atherosclerotic disease needs to be established by prospective, placebo-controlled clinical trials.
Estrogen and progesterone receptors in breast cancer microsamples simultaneously quantified by enzyme-ligand immunoassay
Authors: Krambovitis E , Hatzidakis G , Hatzoglou A , Romain S , Durand A , Stefanakis A , Castanas E 
Published: January 2020

Abstract
A new method (enzyme-ligand immunoassay, ELIA) is described for the estimation of estrogen (ER) and progesterone (PR) receptors in microsamples of human breast cancer tissue. The technique, based on the nonisotopic measurement of receptor-bound estradiol and progesterone, involves three steps: (a) simultaneous saturation of active receptors with their respective authentic ligands, (b) heat treatment of the cytosol to release the steroids from their cognate receptors before or after absorption with dextran-coated charcoal, and (c) measurement of both steroids present in the cytosol by a modified competitive-inhibition enzyme immunoassay. The useful range of the method was 10-4000 pmol/L for ER and 6.5-1000 pmol/L for PR. The correlation coefficient (r) between the one-point and Scatchard plot analysis was 0.95 for ER and 0.99 for PR. Comparison of the one-point ELIA and expected values with the radioligand binding assay (RLBA) results for EORTC samples gave r = 0.88 and 0.99 for ER and PR, respectively. Further comparison of the one-point ELIA with RLBA and with a commercial enzyme immunoassay, in blind testing of cancer tissue microsamples from 70 patients, gave good agreement for ER with r = 0.95-0.97 and concordance of 92.9-94.4% (cutoff, 15 pmol/g protein) against the other two methods. The results were more disperse in all three methods for PR estimation, the assay correlating perhaps better with the enzyme immunoassay (r = 0.90) at a concordance of 89.4% (same cutoff value).