bluuebunny/crossref_metadata_2025_split huggingface dataset:
Usefulness of Saliva for Measurement of 3,4-Methylenedioxymethamphetamine and Its Metabolites: Correlation with Plasma Drug Concentrations and Effect of Salivary pH
Authors: Navarro Mèonica , Pichini Simona , Farré Magí , Ortuño Jordi , Roset Pere N , Segura Jordi , de la Torre Rafael 
Published: January 2020

AbstractBackground: Saliva is an alternative biologic matrix for drugs-of-abuse testing that offers the advantages of noninvasive, rapid, and easy sampling. We studied the excretion profile of 3,4-methylenedioxymethamphetamine (MDMA) and its metabolites in both saliva and plasma, as well the effect of the drug on salivary pH.Methods: Saliva and plasma samples were obtained from eight healthy MDMA consumers after ingestion of a single 100-mg dose of the drug. Concentrations of MDMA and its main metabolites, 3,4-methylenedioxyamphetamine (MDA) and 4-hydroxy-3-methoxymethamphetamine (HMMA), in saliva and plasma were measured by gas chromatography-mass spectrometry. Apparent pharmacokinetic parameters for MDMA in saliva were estimated, and the saliva-to-plasma ratio at each time interval was calculated and correlated with salivary pH.Results: MDMA, MDA, and HMMA were detected in saliva. Salivary concentrations of MDMA were 1728.9–6510.6 μg/L and peaked at 1.5 h after drug intake. This was followed by a progressive decrease, with a mean concentration of 126.2 μg/L at 24 h. The saliva-to-plasma ratio was 32.3–1.2, with a peak of 18.1 at 1.5 h after drug administration. Salivary pH seemed to be affected by MDMA administration; pH values decreased by 0.6 units (mean pH values of 6.9 and 6.8 at 1.5 and 4 h after drug administration vs predose pH of 7.4).Conclusions: Measurement of MDMA in saliva is a valuable alternative to determination of plasma drug concentrations in both clinical and toxicologic studies. On-site testing is also facilitated by noninvasive and rapid collection of salivary specimens.
Reference Centiles for Serum Ferritin and Percentage of Transferrin Saturation, with Application to Mutations of the HFE Gene
Authors: Koziol James A , Ho Ngoc J , Felitti Vincent J , Beutler Ernest 
Published: January 2020

Abstract
Background: The gene that causes most cases of hereditary hemochromatosis is designated HFE. Individuals with mutations in the HFE gene may have increased serum iron, transferrin saturation, and ferritin concentrations relative to individuals with the wild-type genotype.
Methods: We generated reference centiles for percentage of transferrin saturation and serum ferritin concentrations in normal (wild-type), healthy Caucasian adults. We then examined transferrin and ferritin concentrations relative to these centiles in 81 individuals homozygous for the major hemochromatosis mutation C282Y and 438 individuals with the compound heterozygous HFE genotype C282Y/H63D.
Results: Serum ferritin concentrations, but not percentage of transferrin saturation, in normal, healthy women tended to increase sharply as they progressed through menopause. Transferrin and serum ferritin centiles for normal, healthy females were lower than the corresponding centiles in normal, healthy males. C282Y homozygotes had abnormally high transferrin saturation and serum ferritin values relative to the wild types. Compound heterozygotes appeared to be a mixture of individuals with unexceptional transferrin and ferritin values and those with abnormally large values similar to the homozygotes, with equal proportions of each.
Conclusions: There are age- and sex-related differences in reference centiles for the percentage of transferrin saturation and serum ferritin concentrations in normal, healthy adults. Individuals homozygous for the C282Y mutation in the HFE gene have abnormal transferrin saturation and serum ferritin values relative to the reference population; penetrance with the compound heterozygotes, as reflected by abnormal transferrin and ferritin values, is less than with the homozygotes.
Profiling of Tryptophan-related Plasma Indoles in Patients with Carcinoid Tumors by Automated, On-Line, Solid-Phase Extraction and HPLC with Fluorescence Detection
Authors: Kema Ido P , Meijer Wim G , Meiborg Gert , Ooms Bert , Willemse Pax H B , de Vries Elisabeth G E 
Published: January 2020

Abstract
Background: Profiling of the plasma indoles tryptophan, 5-hydroxytryptophan (5-HTP), serotonin, and 5-hydroxyindoleacetic acid (5-HIAA) is useful in the diagnosis and follow-up of patients with carcinoid tumors. We describe an automated method for the profiling of these indoles in protein-containing matrices as well as the plasma indole concentrations in healthy controls and patients with carcinoid tumors.
Methods: Plasma, cerebrospinal fluid, and tissue homogenates were prepurified by automated on-line solid-phase extraction (SPE) in Hysphere Resin SH SPE cartridges containing strong hydrophobic polystyrene resin. Analytes were eluted from the SPE cartridge by column switching. Subsequent separation and detection were performed by reversed-phase HPLC combined with fluorometric detection in a total cycle time of 20 min. We obtained samples from 14 healthy controls and 17 patients with metastasized midgut carcinoid tumors for plasma indole analysis. In the patient group, urinary excretion of 5-HIAA and serotonin was compared with concentrations of plasma indoles.
Results: Within- and between-series CVs for indoles in platelet-rich plasma were 0.6–6.2% and 3.7–12%, respectively. Results for platelet-rich plasma serotonin compared favorably with those obtained by single-component analysis. Plasma 5-HIAA, but not 5-HTP was detectable in 8 of 17 patients with carcinoid tumors. In the patient group, platelet-rich plasma total tryptophan correlated negatively with platelet-rich plasma serotonin (P = 0.021; r = −0.56), urinary 5-HIAA (P = 0.003; r = −0.68), and urinary serotonin (P &lt;0.0001; r = −0.80).
Conclusions: The present chromatographic approach reduces analytical variation and time needed for analysis and gives more detailed information about metabolic deviations in indole metabolism than do manual, single-component analyses.
Tandem Mass Spectrometric Analysis for Amino, Organic, and Fatty Acid Disorders in Newborn Dried Blood Spots
Authors: Zytkovicz Thomas H , Fitzgerald Eileen F , Marsden Deborah , Larson Cecilia A , Shih Vivian E , Johnson Donna M , Strauss Arnold W , Comeau Anne Marie , Eaton Roger B , Grady George F 
Published: January 2020

Abstract
Background: Tandem mass spectrometry (MS/MS) is rapidly being adopted by newborn screening programs to screen dried blood spots for &gt;20 markers of disease in a single assay. Limited information is available for setting the marker cutoffs and for the resulting positive predictive values.
Methods: We screened &gt;160 000 newborns by MS/MS. The markers were extracted from blood spots into a methanol solution with deuterium-labeled internal standards and then were derivatized before analysis by MS/MS. Multiple reaction monitoring of each sample for the markers of interest was accomplished in ∼1.9 min. Cutoffs for each marker were set at 6–13 SD above the population mean.
Results: We identified 22 babies with amino acid disorders (7 phenylketonuria, 11 hyperphenylalaninemia, 1 maple syrup urine disease, 1 hypermethioninemia, 1 arginosuccinate lyase deficiency, and 1 argininemia) and 20 infants with fatty and organic acid disorders (10 medium-chain acyl-CoA dehydrogenase deficiencies, 5 presumptive short-chain acyl-CoA dehydrogenase deficiencies, 2 propionic acidemias, 1 carnitine palmitoyltransferase II deficiency, 1 methylcrotonyl-CoA carboxylase deficiency, and 1 presumptive very-long chain acyl-CoA dehydrogenase deficiency). Approximately 0.3% of all newborns screened were flagged for either amino acid or acylcarnitine markers; approximately one-half of all the flagged infants were from the 5% of newborns who required neonatal intensive care or had birth weights &lt;1500 g.
Conclusions: In screening for 23 metabolic disorders by MS/MS, an mean positive predictive value of 8% can be achieved when using cutoffs for individual markers determined empirically on newborns.
Oligonucleotide Melting Temperatures under PCR Conditions: Nearest-Neighbor Corrections for Mg2+, Deoxynucleotide Triphosphate, and Dimethyl Sulfoxide Concentrations with Comparison to Alternative Empirical Formulas
Authors: von Ahsen Nicolas , Wittwer Carl T , Schütz Ekkehard 
Published: January 2020

Abstract
Background: Many techniques in molecular biology depend on the oligonucleotide melting temperature (Tm), and several formulas have been developed to estimate Tm. Nearest-neighbor (N-N) models provide the highest accuracy for Tm prediction, but it is not clear how to adjust these models for the effects of reagents commonly used in PCR, such as Mg2+, deoxynucleotide triphosphates (dNTPs), and dimethyl sulfoxide (DMSO).
Methods: The experimental Tms of 475 matched or mismatched target/probe duplexes were obtained in our laboratories or were compiled from the literature based on studies using the same real-time PCR platform. This data set was used to evaluate the contributions of [Mg2+], [dNTPs], and [DMSO] in N-N calculations. In addition, best-fit coefficients for common empirical formulas based on GC content, length, and the equivalent sodium ion concentration of cations [Na+eq] were obtained by multiple regression.
Results: When we used [Na+eq] = [Monovalent cations] + 120($\batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(\sqrt{{[}Mg^{2{+}}{]}\ {-}\ {[}dNTPs{]}}\) \end{document}$) (the concentrations in this formula are mmol/L) to correct ΔS0 and a DMSO term of 0.75 °C (%DMSO), the SE of the N-N Tm estimate was 1.76 °C for perfectly matched duplexes (n = 217). Alternatively, the empirical formula Tm (°C) = 77.1 °C + 11.7 × log[Na+eq] + 0.41(%GC) − 528/bp − 0.75 °C(%DMSO) gave a slightly higher SE of 1.87 °C. When all duplexes (matched and mismatched; n = 475) were included in N-N calculations, the SE was 2.06 °C.
Conclusions: This robust model, accounting for the effects of Mg2+, DMSO, and dNTPs on oligonucleotide Tm in PCR, gives reliable Tm predictions using thermodynamic N-N calculations or empirical formulas.
Creatine Kinase Gene Mutation in a Patient with Muscle Creatine Kinase Deficiency
Authors: Yamamichi Hiroshi , Kasakura Shinpei , Yamamori Shunzi , Iwasaki Ryu , Jikimoto Takumi , Kanagawa Sugayo , Ohkawa Jiro , Kumagai Shunichi , Koshiba Masahiro 
Published: January 2020

AbstractBackground: We describe a 56-year-old woman admitted to the hospital with a diagnosis of acute myocardial infarction without an increase of serum creatine kinase (CK) activity during her clinical course. She died on the 11th hospital day, and the diagnosis was confirmed by autopsy. The patient had had no previous muscular symptoms.Methods: Expression of the CK-muscle (CK-M) protein in cardiac tissue was examined by immunoblotting and immunochemical staining. CK-M mRNA expression was estimated by semiquantitative reverse transcription–PCR. Gene structure of CK-M was determined by Southern blotting and direct sequencing of 2251 bp. Existence of a point mutation in the CK-M gene was examined by restriction fragment length polymorphism analysis of PCR products (PCR-RFLP) in the patient and in 108 controls.Results: CK-M protein in the myocardial tissue of the patient was substantially lower (103 ± 7 ng/mg protein) than in control myocardial tissue (35 800 ± 2860 ng/mg protein). Immunoreactive CK-M in the patient tissue sample was 0.3% of the value for the control sample. CK-M mRNA was 53-fold less in the patient sample compared with the control. This very low expression of CK-M mRNA was considered to be the primary reason for CK-M deficiency. Direct sequencing revealed a point mutation at residue 54 in exon 2, which was specific for the patient. No other abnormalities were found in the CK-M gene of the patient.Conclusions: This report identifies a molecular abnormality in human CK deficiency and discusses the physiologic relevance of CK-M.
Analysis of Dicarboxylic Acids by Tandem Mass Spectrometry. High-Throughput Quantitative Measurement of Methylmalonic Acid in Serum, Plasma, and Urine
Authors: Kushnir Mark M , Komaromy-Hiller Gabor , Shushan Bori , Urry Francis M , Roberts William L 
Published: January 2020

Abstract
Background: Methylmalonic acid (MMA) is a dicarboxylic acid whose concentration can be increased in blood and urine in patients with an inborn error of metabolism or vitamin B12 deficiency. We developed a method for the selective analysis of dicarboxylic acids that exploits the high specificity of tandem mass spectrometry (MS/MS) and the substantial difference in fragmentation patterns of the isomers methylmalonic (MMA) and succinic acid (SA).
Methods: Dicarboxylic acids were extracted from samples with methyl-tert-butyl ether and derivatized with butanolic HCl to form dibutyl esters. The derivative was injected into the liquid chromatography (LC)-MS/MS system using TurboIonSprayTM (nebulizer-assisted electrospray) ionization and quantified by the multiple reaction monitoring mode of MS/MS.
Results: The assay for MMA was linear up to 150 μmol/L. The total imprecision was ≤7.5% at both low and high concentrations. The limits of quantification and detection were 0.1 and 0.05 μmol/L, respectively. The degree of interference from SA could be predicted from the branching ratios of the major product ions.
Conclusions: The method is specific for dicarboxylic acids. The LC-MS/MS analysis for MMA requires minimal chromatographic separation and takes &lt;60 s per sample. The entire analysis, including sample preparation, for a batch of 100 specimens can be performed in &lt;4 h.
Fatty Acid Ethyl Esters in Hair as Markers of Alcohol Consumption. Segmental Hair Analysis of Alcoholics, Social Drinkers, and Teetotalers
Authors: Auwärter Volker , Sporkert Frank , Hartwig Sven , Pragst Fritz , Vater Hannelore , Diefenbacher Albert 
Published: January 2020

AbstractBackground: Fatty acid ethyl esters (FAEEs) are products of nonoxidative ethanol metabolism. After incorporation in hair, they should be suitable long-term markers of alcohol abuse.Methods: Hair samples from 19 alcoholics in a treatment program, 10 fatalities with verified excessive alcohol consumption, 13 moderate social drinkers who consumed up to 20 g ethanol/day, and 5 strict teetotalers were analyzed in 1–12 segments for four FAEEs (ethyl myristate, ethyl palmitate, ethyl oleate, and ethyl stearate) by external degreasing with n-heptane, extraction with a dimethyl sulfoxide-n-heptane mixture, headspace solid-phase microextraction of the extracts, and gas chromatography-mass spectrometry with deuterated internal standards. The n-heptane washings were analyzed in the same way for FAEEs from the hair surface.Results: The sum of the four ester concentrations in hair calculated for the proximal 0–6 cm segment was 2.5–13.5 ng/mg (mean, 6.8 ng/mg) for the fatalities, 0.92–11.6 ng/mg (mean, 4.0 ng/mg) for 17 of the alcoholics in treatment, 0.20–0.85 ng/mg (mean, 0.41 ng/mg) for the moderate social drinkers, and 0.06–0.37 ng/mg (mean, 0.16 ng/mg) for the teetotalers. In almost all cases the segmental concentrations increased from proximal to distal. There was no agreement between the self-reported drinking histories of the participants and the FAEE concentrations along the hair length. Ethyl oleate was the dominant ester in all samples.Conclusions: FAEEs are deposited in hair mainly from sebum. Despite large individual differences, FAEE hair concentrations can be used as markers for excessive alcohol consumption with relatively high accuracy.
Effects of Hemoglobin Variants and Chemically Modified Derivatives on Assays for Glycohemoglobin
Authors: Bry Lynn , Chen Philip C , Sacks David B 
Published: January 2020

AbstractBackground: Glycohemoglobin (gHb), measured as hemoglobin (Hb) A1c or as total gHb, provides a common means for assessing long-term glycemic control in individuals with diabetes mellitus. Genetic variants and chemically modified derivatives of Hb can profoundly affect the accuracy of these measurements, although effects vary considerably among commercially available methods. The prevalence of genetic variants such as HbS, HbC, and HbE, and chemically modified derivatives such as carbamyl-Hb among patient populations undergoing testing is not insignificant. Clinical laboratories and sites responsible for point-of-care testing of gHb need to be aware of the interferences produced in assays by these Hbs.Approach: We conducted a review of the literature describing the effects of variant Hbs on gHb assay methods commonly used in clinical laboratories.Content: This review summarizes the documented effects of both common and uncommon Hb variants and derivatives on the measurement of gHb. Where known, we discuss mechanisms of interference on specific assays and methodologies. We specifically address effects of commonly encountered Hbs, such as carbamyl-Hb, HbS, HbC, HbE, and HbF, on assays that use cation-exchange chromatography, immunoassays, or boronate affinity methods for measuring gHb.Summary: A variety of patient- and laboratory-related factors can adversely affect the measurement of gHb in patients harboring Hb variants or derivatives. Identification of the variant or derivative Hb before or during testing may allow accurate measurement of gHb by the selection of a method unaffected by the given variant or derivative. However, laboratories should make available alternative, non-Hb-based methods for assessing long-term glycemic control in individuals with HbCC, HbSS, or HbSC disease, or with other underlying disorders where the concentration of gHb does not accurately reflect long-term glycemic control.
Quantitative Real-Time Reverse Transcription-PCR Assay for Cyclin D1 Expression: Utility in the Diagnosis of Mantle Cell Lymphoma
Authors: Bijwaard Karen E , Aguilera Nadine S I , Monczak Yury , Trudel Michel , Taubenberger Jeffery K , Lichy Jack H 
Published: January 2020

AbstractBackground: The t(11;14)(q13;q32) translocation present in the majority of mantle cell lymphomas (MCLs) places the cyclin D1 gene under the control of immunoglobulin transcriptional regulatory elements, causing overexpression of cyclin D1. Quantification of cyclin D1 expression can distinguish MCL from other lymphomas.Methods: A quantitative real-time reverse transcription (RT)-PCR assay was developed for cyclin D1 mRNA suitable for use with RNA extracted from fresh and formalin-fixed, paraffin-embedded tissues. Specimens were amplified in an Applied Biosystems Model 7700 Sequence Detection System in reactions containing primers and probes for cyclin D1 and a control gene, β2-microglobulin. Relative expression of the two genes was standardized against a control MCL cell line, M02058.Results: The range of cyclin D1 expression among 20 MCLs was substantially higher than that in other lymphomas and reactive lymph nodes. By choosing an optimal cutoff point for assessing overexpression, the sensitivity and specificity of the assay for the diagnosis of MCL in lymph node specimens both approached 100%: Overexpression was detected in 20 of 20 MCLs, but in none of 21 non-mantle-cell lymphomas or 10 reactive lymph nodes.Conclusions: Quantitative real-time RT-PCR for cyclin D1 overexpression provides a rapid diagnostic test with clinical utility in the diagnosis of MCL.
Macromolecular Chromogenic Substrates for Measuring Proteinase Activity
Authors: Hortin Glen L , Warshawsky Ilka , Laude-Sharp Maryline 
Published: January 2020

AbstractBackground: Proteinase activities are often measured using chromogenic substrates that are much smaller than physiological substrates.Methods: The hydrodynamic size of macromolecular substrates (macrosubstrates) prepared by linking small chromogenic substrates to polyethylene glycol was determined by gel filtration. Efficiency of macrosubstrate cleavage by proteinases and α2-macroglobulin-proteinase complexes was monitored spectrophotometrically.Results: Macrosubstrates had hydrodynamic radii of ∼20 Å, similar to proteins with a molecular weight of 18 000. Different macrosubstrates served as efficient substrates for chymotrypsin, trypsin, and thrombin. Linking small substrates to a polymer variably affected substrate efficiency, with the impact on activity ranging from a 60-fold decrease to a 30-fold increase. Proteinases complexed with α2-macroglobulin had ∼10-fold lower activity vs macrosubstrates than small substrates.Conclusions: Macrosubstrates are efficient substrates that allow decreased measurement of sterically hindered proteinase molecules such as α2-macroglobulin-proteinase complexes. Thus, macrosubstrates may provide more accurate functional assays of proteinases such as coagulation factors.
Quantitative Determination of Vapor-Phase Compound A in Sevoflurane Anesthesia Using Gas Chromatography–Mass Spectrometry
Authors: Bouche Marie-Paule L A , Van Bocxlaer Jan F P , Rolly Georges , Versichelen Linda F M , Struys Michel M R F , Mortier Eric , De Leenheer André P 
Published: January 2020

Abstract
Background: During low-flow or closed-circuit anesthesia with the fluorinated inhalation anesthetic sevoflurane, compound A, an olefinic degradation product with known nephrotoxicity in rats, is generated on contact with alkaline CO2 adsorbents. To evaluate compound A formation and thus potential sevoflurane toxicity, a reliable and reproducible assay for quantitative vapor-phase compound A determination was developed.
Methods: Compound A concentrations were measured by fully automated capillary gas chromatography–mass spectrometry with cryofocusing. Calibrators of compound A in the vapor phase were prepared from liquid volumetric dilutions of stock solutions of compound A and sevoflurane in ethyl acetate. 1,1,1-Trifluoro-2-iodoethane was chosen as an internal standard. The resulting quantitative method was fully validated.
Results: A linear response over a clinically useful concentration interval (0.3–75 μL/L) was obtained. Specificity, sensitivity, and accuracy conformed with current analytical requirements. The CVs were 4.1–10%, the limit of detection was 0.1 μL/L, and the limit of quantification was 0.3 μL/L. Analytical recoveries were 100.6% ± 10.1%, 102.5% ± 7.3%, and 99.0% ± 4.1% at 0.5, 10, and 75 μL/L, respectively. The method described was used to determine compound A concentrations during simulated closed-circuit conditions. Some of the resulting data are included, illustrating the practical applicability of the proposed analytical approach.
Conclusions: A simple, fully automated, and reliable quantitative analytical method for determination of compound A in air was developed. A solution was established for sampling, calibration, and chromatographic separation of volatiles in an area complicated by limited availability of sample volume and low concentrations of the analyte.