bluuebunny/crossref_metadata_2025_split huggingface dataset:
Versatile, efficient system for extracting drugs from urine for gas chromatographic/mass spectrometric analysis.
Authors: Brooks K E , Smith N B 
Published: January 2020

Abstract
This is a method for efficiently extracting a wide variety of drugs from urine for toxicological analysis by gas chromatography/mass spectrometry. Before extraction, the urine sample is acetylated, diluted with an equal volume of water, and saturated with NaCl. This solution is then mixed with an equal volume of dichloromethane/acetone (2:1 by vol). The organic (top) phase is aspirated and evaporated, and the residue is redissolved in a suitable solvent for injection or further derivatization. This procedure is suitable for all drugs except carboxylate-containing drugs, which may be isolated by replacing the acetylation step with acidification of the urine to pH 2. Studies with 16 drugs containing amino, amide, alcoholic hydroxyl, phenolic hydroxyl, carboxylate groups, or combinations thereof, showed that all drugs except theophylline and benzoylecgonine were extracted with analytical recoveries ranging from 70% to 100%.
Extending the detection limit of the TDx fluorescence polarization immunoassay for benzoylecgonine in urine.
Authors: de Kanel J , Dunlap L , Hall T D 
Published: January 2020

Abstract
This modified calibration method decreases from 300 to 27 micrograms/L the limit of detection for the cocaine metabolite (hydrolysis product), benzoylecgonine, by the Abbott Laboratories TDx fluorescence polarization immunoassay. For this determination we used 30 controls prepared from a single urine pool known to be negative for cocaine metabolite. Assay of 80 controls prepared from 20 different patients' urine samples yielded a limit of detection of 44 micrograms/L. To test these limits of detection, we analyzed 90 patients' urine samples known to be negative for cocaine metabolite and 74 patients' samples known to be positive for cocaine metabolite, using the TDx with our revised calibration. Results for two of the known negative samples and 96% of the samples containing cocaine in the 50 to 100 micrograms/L range fell above the 44 micrograms/L limit. The TDx showed excellent calibration stability. For 28 days during the test, the instrument was not recalibrated. During this period the day-to-day analysis of 50 micrograms/L controls produced a mean TDx response of 0.485 (SD 0.007) with a coefficient of variation of 1.5%.
Molecular genetics and the transformation of clinical chemistry.
Authors: Williamson R 
Published: January 2020

Abstract
Clinical chemistry is going through an identity crisis, squeezed between automation (de-skilling) on the service side and molecular genetics in research. Automated routine estimations are now carried out and interpreted by machines; the skilled staff members required are more likely to have degrees in electronics than medicine or biochemistry. The role of molecular genetics is more ambiguous; it is inherently reductionist, in that it attempts to explain most clinical phenomena in terms of DNA sequence alone. This has been remarkably successful for single-gene defects (such as those causing Duchenne muscular dystrophy, hemoglobinopathies, cystic fibrosis, and ataxias) and may well prove equally so for Alzheimer's disease, cancer, heart disease, and schizophrenia. DNA diagnosis is not yet routine, but because of technical advances such as gene amplification ("PCR") and high-sensitivity gene-detection assays, it may soon become so, not only in major centers but also in local pathology laboratories and general practice. Clinical chemists must decide whether they wish to respond to this new and stimulating challenge by retooling and retraining. Should anyone be permitted into clinical chemistry during the 1990s without knowledge of both electronics and molecular genetics? Will there be a clinical chemistry in the twenty-first century other than through molecular genetics? This article is a personal response to these questions.
Determination of alpha 2-macroglobulin-trypsin complex with a new synthetic substrate.
Authors: Kuroiwa K , Nakatsuyama S , Katayama K , Nagasawa T 
Published: January 2020

Abstract
We have developed a colorimetric assay for quantifying alpha 2-macroglobulin-trypsin complex (alpha 2M-TRY) in human serum, based on use of a new chromogenic substrate D-gamma-tert-butyloxy-Glu-Gly-Arg-3-carboxy-4-hydroxyanilide dihydrochloride (PS-3001). Within-run CVs by this assay were 4.76%, 1.57%, and 0.83% for trypsin complex concentrations of 3.1, 12.2, and 48.1 U/L, respectively (n = 10 each). Between-day CVs were 5.38%, 3.12%, and 2.20% at each concentration, respectively (n = 7). Mean analytical recoveries of alpha 2M-TRY added to serum were 100%, 105%, and 101% for 9.2, 15.1, and 46.3 U/L, respectively (n = 2). The standard curve obtained was linear up to 330 U/L. We applied this method to the study of alpha 2M-TRY activity in sera from 97 healthy subjects (group 1), from 27 patients with acute pancreatitis (group 2), and from 25 patients with other chylopoietic diseases (group 3); results ranged from 0 to 1.2 U/L (mean = 0.5, SD = 0.3), from 1.2 to 77.4 U/L (mean = 14.6, SD = 19.0), and from 0 to 1.3 U/L (mean = 0.4, SD = 0.3), respectively. Concentrations of enzymatically active alpha 2M-TRY were significantly greater in sera from group 2 than in groups 1 and 3. The determination of serum alpha 2M-TRY activity by this simple, rapid, colorimetric method may be useful for the diagnosis and evaluation of pancreatic disease.
Characteristics of creatine kinase-MB and MB isoforms in serum after reperfusion in acute myocardial infarction.
Authors: Christenson R H , Ohman E M , Clemmensen P , Grande P , Toffaletti J , Silverman L M , Vollmer R T , Wagner G S 
Published: January 2020

Abstract
Characteristics of CK-MB, the MB1 and MB2 isoforms, and the MB2/MB1 ratio are described in six acute myocardial infarction (AMI) patients in whom the infarct-related artery was identified and, after intervention, normal coronary flow was re-established. After myocardial reperfusion, washout of CK-MB and the MB2 isoform occurred in parallel, with CK-MB peaking between 5.75 and 10.0 h, and MB2 peaking between 4.50 and 8.00 h. In five of the six patients, MB1 peaked between 8.75 and 15.5 h; the MB2/MB1 ratio demonstrated the earliest peak from 0.75 to 2.25 h. When we compared this study group to an additional 10 AMI patients who had achieved myocardial reperfusion earlier, we found a significant difference (P less than 0.005) for all tests, except MB1 isoform activity, as early as 50 min after reperfusion. This same comparison, by logistic-regression analysis, showed that the MB2/MB1 ratio discriminated between the groups 50 min after reperfusion (P less than 0.05); MB2 showed near-significance at 100 min (P less than 0.057); and CK-MB achieved significance after 200 min (P less than 0.05). CK-MB, the MB2 isoform, and especially the MB2/MB1 ratio show potential for the early, noninvasive detection of myocardial reperfusion.
Automated DNA sequencing methods involving polymerase chain reaction.
Authors: McBride L J , Koepf S M , Gibbs R A , Salser W , Mayrand P E , Hunkapiller M W , Kronick M N 
Published: January 2020

Abstract
Polymerase chain reaction (PCR) as a method for preparing DNA templates has been used for several DNA sequencing applications. An in situ procedure for directly sequencing PCR products by the dideoxy-termination method has been developed by using fluorophore-labeled sequencing primers. Completed sequence reactions were combined and loaded into a single electrophoretic lane of a fluorescence-based DNA sequence analyzer. DNA targets devoid of a universal primer sequence could be sequenced with labeled universal primers by incorporating a universal primer sequence into the PCR product. With this method, the sequence of a 351-bp region in the bacteriophage lambda genome was fully analyzed in a single lane with automatic base identification accuracy of greater than 99%. An unknown sequence, 1.7 kb long, also was sequenced by this procedure, in combination with a "PCR gene walking" strategy. Comparison of the 1110 bases in overlapping sequence data from both strands yielded only two single-base ambiguities. Automated DNA sequence analysis of the highly polymorphic HLA-DQA-1 (alpha) region in the human genome can be performed with this simple methodology. Use of this PCR-sequencing method to analyze DNA extracted from a one-month-old blood sample from an individual who is heterozygous at this locus allowed unambiguous assignment of genotype.
Enzymatic assay of magnesium through glucokinase activation.
Authors: Fossati P , Sirtoli M , Tarenghi G , Giachetti M , Berti G 
Published: January 2020

Abstract
We describe an improved enzymatic method for assaying magnesium in serum, plasma, or urine. Magnesium participates as an Mg.ATP complex in a reaction catalyzed by glucokinase (EC 2.7.1.2) coupled to an NADP+-dependent glucose-6-phosphate dehydrogenase (EC 1.1.1.49) reaction. The increase of absorbance at 340 nm, due to the NADPH produced, is proportional to the amount of the activated glucokinase, which in turn is related to the concentration of magnesium in the sample. The method is characterized by a zero-order reaction kinetics, affording a simple and rapid assay with good sensitivity and linearity (up to 2.06 mmol/L) and by working solutions that are stable (refrigerated) for one month. The method is reliable, produces test results that compare closely with those of the atomic absorption spectrophotometry (r greater than or equal to 0.99), is suitable for routine work, and lends itself to automation.
Decreased dehydroepiandrosterone sulfate in pigmented nodular adrenal dysplasia.
Authors: Braithwaite S S , Collins S , Prinz R A , Walloch J L , Winters G L 
Published: January 2020

Abstract
Previous reports on patients with endogenous Cushing's syndrome describe low concentrations of the adrenal androgen dehydroepiandrosterone sulfate (DHEA-S) in adrenal adenoma and in a case of feminizing macronodular hyperplasia. Here we present hormonal data from two adult sisters with Cushing's syndrome as a result of pigmented nodular adrenal dysplasia. Corticotropin concentrations were in the mid-normal range, cortisol production was unaffected by administration of dexamethasone (8 mg/24 h), and baseline concentrations of DHEA-S were less than 0.5 mumol/L. A low concentration of DHEA-S in these and other previously reported patients with Cushing's syndrome correctly predicts the results of dynamic testing. Decreased DHEA-S in a patient with endogenous Cushing's syndrome can be ascertained by assay of a single sample and should prompt consideration of the diagnosis of autonomous bilateral nodular disease as well as adrenal adenoma.
Simple enzymatic determination of total cholesterol in gallstones.
Authors: Wei J S , Huang H M , Shyu W C , Wu C S 
Published: January 2020

Abstract
In this simple method for rapid enzymatic determination of total cholesterol in human gallstones, gallstone powder is dissolved in an 80/20 by vol mixture of N,N-dimethylformamide and dimethyl sulfoxide and reacted directly with the aqueous enzymatic reagent, without further treatment. The organic solvents do not interfere with enzymatic activities of cholesterol oxidase, esterase, and peroxidase in the assay mixture. The method is reproducible (CVs 3.7% to 6.6%), analytical recoveries ranged from 98.6% to 102%, and linearity is good. Furthermore, results correlated well with those obtained by infrared spectroscopic measurements.
Macroenzymes: biochemical characterization, clinical significance, and laboratory detection.
Authors: Remaley A T , Wilding P 
Published: January 2020

Abstract
"Macroenzymes" are enzymes in serum that have formed high-molecular-mass complexes, either by self-polymerization or by association with other serum components. Many enzymes in serum that are measured in clinical chemistry laboratories can occur in a macroenzyme form. Macroenzymes are interesting clinically because of their association with several diseases, including autoimmune diseases and liver disease, and are being investigated as possible diagnostic markers. Most importantly, macroenzymes frequently interfere with the interpretation of serum enzyme results, and as a result can cause diagnostic and therapeutic errors. We review the biochemical characterization, clinical significance, and laboratory detection of macroenzymes.
Steroid profile for urine: reference values.
Authors: Weykamp C W , Penders T J , Schmidt N A , Borburgh A J , van de Calseyde J F , Wolthers B J 
Published: January 2020

Abstract
We describe a project, participated in by 24 institutions in The Netherlands and Belgium, to determine normal reference values for steroids in urine by capillary gas chromatography. Urine samples from 288 healthy volunteers were analyzed in triplicate. Reference values, expressed in mumol/24 h, were determined for androsterone, etiocholanolone, dehydroepiandrosterone, 11-keto-androsterone, 11-keto-etiocholanolone, 11-hydroxyandrosterone, 11-hydroxyetiocholanolone, pregnanediol, pregnanetriol, 11-desoxytetrahydrocortisol, tetrahydrocortisone, tetrahydrocortisol, allo-tetrahydrocortisol, and 17-keto- and 17-hydroxysteroids. We also determined reference ratios for etiocholanolone/androsterone, tetrahydrocortisone/tetrahydrocortisol, and tetrahydrocortisol/allo-tetrahydrocortisol; an upper limit of a discriminant function to establish polycystic ovarian disease; and reference values for 24-h urine volume and creatinine excretion. Reference values were determined separately for men and women, each in six age categories: 0-3 months, 4 months-12 years, 13-16 years, 17-50 years, 51-70 years, and older than 70 years. We conclude that these reference values are reliable and form a basis for quantitative interpretation of steroid profiles.
Free 3-methoxy-4-hydroxyphenylglycol determined in plasma by liquid chromatography with coulometric detection.
Authors: Hariharan M , VanNoord T , Cameron O G , Curtis G C , Ostrow D G 
Published: January 2020

Abstract
We describe a simple "high-performance" liquid-chromatographic method for determining free 3-methoxy-4-hydroxyphenylglycol (MHPG) in plasma, with coulometric detection and with 4-methoxy-3-hydroxyphenylglycol (iso-MHPG) as the internal standard. MHPG and iso-MHPG are extracted from plasma into ethyl acetate and the extract is washed with a sodium bicarbonate solution, evaporated, reconstituted, and injected into a 25 x 0.4 cm column packed with 3-micron particles of C18 material. We used a mobile phase of acetate buffer (100 mmol/L, pH 5.0) and methanol (92:8 by vol) and an oxidation voltage of 0.5 V. The detection limit of the assay is 0.1 micrograms/L. The interassay CV for a sample with a mean MHPG concentration of 3.84 micrograms/L was 5.2%. The average absolute recovery for the method was 37%.
Heterogeneity of serum creatine kinase isoenzyme MM in myocardial infarction: clinical significance and post-synthetic conversion of "abnormal" sub-bands.
Authors: Williams J , Williams K M , Marshall T 
Published: January 2020

Abstract
We investigated the "abnormal" sub-bands of serum creatine kinase (CK; EC 2.7.3.2) isoenzyme MM in acute myocardial infarction (AMI), using isoelectric focusing in polyacrylamide gels, and compared the patterns with those for non-AMI patients and for athletes with increased CK. The "abnormal" sub-bands a (pI 7.55), b (pI 7.35), c (pI 7.25), d (pI 7.05), e (pI 6.85), f (pI 6.72), g (pI 6.50), h (pI 6.40), i (pI 6.28), j (pI 6.20), and k (pI 6.15), in common with "normal" sub-bands 1 (pI 6.91), 2 (pI 6.65), and 3 (pI 6.35), were less uniformly distributed in the AMI and demonstrated a faster rate of anodal conversion than in the non-AMI patients and athletes. "Abnormal" sub-bands a and b were detected only in the AMI patients. Incubation of myocardial CK-MM, predominantly CK-MM 1, with 2-mercaptoethanol, 15 mmol/L, resulted in conversion to the "abnormal" sub-bands b and c. Incubation of myocardial CK-MM with normal serum of low total CK yielded CK-MM 3, which on further incubation with 2-mercaptoethanol, 15 mmol/L, resulted in conversion to the "abnormal" sub-bands f and g. Comparable in vitro incubation of serum from AMI patients gave pattern changes consistent with conversion of CK-MM 1 to b, c; CK-MM 2 to d, e; and CK-MM 3 to f, g.
Optimized microturbidimetric assay for fibrinogen.
Authors: Macart M , Koffi A , Henocque G , Mathieu J F , Guilbaud J C 
Published: January 2020

Abstract
In this assay we measure the turbidity produced by precipitation of plasma fibrinogen with a reagent composed of ammonium sulfate, EDTA, and guanidine hydrochloride. The two-step reagent addition, and use of fixed reaction times, eliminates interference from bilirubin, hemoglobin, and chylomicrons. We checked 135 monoclonal proteins for interference, finding the probability of encountering major interference in samples from adults to be very low, P = 0.0002. The method is calibrated with purified fibrinogen and the response is linear over the range 0-10 g/L. Within-run precision (CV) is less than 2% from 1 to 10 g/L. Correlations with the immunoturbidimetric (r = 0.99), chronometric (r = 0.99), and clotting (r = 0.97) methods were extremely high.
Nonenzymatic stopped-flow fluorimetric method for direct determination of uric acid in serum and urine.
Authors: Pérez-Bendito D , Gómez-Hens A , Gutiérrez M C , Antón S 
Published: January 2020

Abstract
A simple, direct, sensitive, and selective stopped-flow method for the fluorimetric determination of uric acid in serum and urine samples is described. The variation of fluorescence intensity during the reaction between uric acid and 1,1,3-tricyano-2-amino-1-propene (triap) in the presence of hydrogen peroxide is monitored. For these kinetic measurements peroxide is monitored. For these kinetic measurements we used a versatile stopped-flow module that can be fitted to any fluorimeter. The linear range of the proposed method is 0.08-3.00 mg of uric acid per liter, and the detection limit is 0.03 mg/L. Within- and between-assay CVs and selectivity data are reported. Results for serum and urine samples correlated well with those obtained by the uricase method The proposed method is inexpensive and requires no sophisticated detection equipment.
Measurement of autoimmune response against collagen types I, III, and IV by enzyme-linked immunosorbent assay, and its application in infective endocarditis.
Authors: De Buyzere M L , De Scheerder I K , Delanghe J R , Robbrecht J H , Clement D L , Wieme R J 
Published: January 2020

Abstract
In these enzyme-linked immunosorbent assays for determination of autoantibodies (IgG, IgM) against collagen type I (ACA I), III (ACA III), and IV (ACA IV), we use commercially available antigen preparations. Inhibition curves showed limited cross-reactivity between these different collagen preparations, the major interference being observed after addition of collagen type III in the ACA I procedures. Imprecision (CVs) for high- and low-titer samples ranged between 1.5% and 7.9% (within-run) and 5.5% and 12.7% (between-run) for ACA I, between 2.2-8.7% and 4.5-10.7% for ACA III, and between 1.3-5.9% and 7.4-11.6% for ACA IV. Significantly increased humoral immune response against collagen types I and III (P less than 0.001) could be demonstrated during the first month of infective endocarditis. In contrast, only borderline increases, however constant, of autoimmune response against basement-membrane collagen (ACA IV) were noticed during 90 days of follow-up.
A dual-precipitation method evaluated for measurement of cholesterol in high-density lipoprotein subfractions HDL2 and HDL3 in human plasma.
Authors: Patsch W , Brown S A , Morrisett J D , Gotto A M , Patsch J R 
Published: January 2020

Abstract
The dual-precipitation method for measurement of cholesterol in high-density lipoprotein subfractions HDL2 and HDL3 (Warnick et al., Clin Chem 1982;28:1574) was compared with quantification of cholesterol in HDL2 and HDL3 by zonal ultracentrifugation (Patsch et al., J Lipid Res 1974;15:356-66). For 39 plasma specimens differing widely in their HDL subfraction cholesterol concentration, the coefficient of correlation between the two methods was 0.94 for HDL2-cholesterol, 0.82 for HDL3-cholesterol. Storage of plasma specimens at -70 degrees C decreased the apparent content of HDL3-cholesterol by 5%; no significant changes in HDL2-cholesterol were observed. In frozen plasma, interference by apoB-containing lipoproteins and by lipoprotein(a) was negligible. Mean weight ratios of apoA-I to cholesterol were twice as high for HDL3 as for HDL2, reflecting the increased cholesterol content of HDL2. The study suggests that quantification of HDL2 and HDL3 cholesterol by precipitation is appropriate for use in epidemiological studies.
Homogentisic acid determined in biological fluids by HPLC.
Authors: Bory C , Boulieu R , Chantin C , Mathieu M 
Published: January 2020

Abstract
In this rapid, specific, and sensitive high-performance liquid-chromatographic method of analysis for homogentisic acid in biological fluids, homogentisic acid is separated on a column of Nucleosil CN. This method, which we applied to the diagnosis of three cases of alcaptonuria, represents a suitable analytical tool for the diagnosis of alcaptonuria.
Factitiously high sodium activities on the Ektachem 400 owing to interferences by high gamma-globulin concentrations.
Authors: Eastep S J , Benson P J , Preese L M , Apple F S 
Published: January 2020

Abstract
Sera from patients with above-normal gamma-globulin concentrations give sodium values as much as 10% higher when measured in the Kodak Ektachem 400 analyzer than results obtained with the Beckman Astra-8 analyzer. Results obtained with the Astra were in agreement with flame photometry. A similar relative bias was observed for potassium measurement in the Ektachem. This discrepancy was corrected when we used a new generation of reference fluid provided by Kodak, which is currently available for general use.
D-lysine effectively decreases the non-enzymic glycation of proteins in vitro.
Authors: Sensi M , Pricci F , De Rossi M G , Morano S , Di Marlo U 
Published: January 2020

Abstract
Excessive non-enzymic glycation of proteins alters their physicochemical properties, with possible pathological effects. We investigated the in vitro inhibition of protein glycation by D-lysine--an isomer not incorporated into mammalian proteins but possessing the same chemical characteristics as L-lysine. Glucose incorporation was studied as follows: (a) human albumin, IgG, collagen, and isolated glomerular basement membrane were incubated for 20 days with D-glucose (5.0, 10.0, and 20.0 mmol/L) in the presence of D-lysine at 1/10 the sugar concentration; (b) albumin was incubated in similar glucose concentrations but with a constant amount (2.0 mmol/L) of D-lysine; (c) albumin and IgG were incubated for 10 days in buffer containing glucose (10 mmol/L) and increasing concentrations of D-lysine (0.25, 0.5, 1.0, 2.0, and 4.0 mmol/L); (d) inhibition specificity was tested by treating albumin as in c but with glycerol present rather than D-lysine. In addition, we measured ketoamine after incubating albumin (50 g/L) in 10 mmol/L glucose for 10 days in the presence of D-lysine (0.25, 0.5, 1.0, and 2.0 mmol/L). The results show that (a) the amount of glucose bound to the four proteins was significantly (P less than 0.05) decreased in the presence of D-lysine at the higher concentrations of glucose; (b) the lower the glucose concentration, the higher was the inhibitory effect of D-lysine; (c) the inhibition of glucose incorporation into proteins correlated directly with the concentration of D-lysine; (d) no inhibition was observed with glycerol. Ketoamine decreased with increase in D-lysine (P less than 0.01). The effective diminution of non-enzymatic glycation by D-lysine highlights its potential use in vivo.