bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of thiol oxidation and thiol export from erythrocytes on determination of redox status of homocysteine and other thiols in plasma from healthy subjects and patients with cerebral infarction
Authors: Andersson A , Lindgren A , Hultberg B 
Published: January 2020

Abstract
Changes in concentration of reduced and oxidized low-M(r) thiols were measured in blood and plasma before and after the separation of blood cells. If centrifugation of blood was postponed, the reduced form of homocysteine in plasma increased with time at 22 degrees C; in contrast, the concentrations of other reduced thiols (cysteine, glutathione, and cysteinylglycine) decreased. In plasma the reduced forms of all thiols disappeared at a rate that followed first-order kinetics. The rates of disappearance ("half-lives") were temperature-dependent; they were about the same for glutathione and homocysteine (11.7 and 14.3 min, respectively, at 22 degrees C) and somewhat higher for cysteinylglycine and cysteine. After establishing proper sampling conditions for reduced thiols, we measured this thiol fraction as well as free (non-protein-bound) and total thiols in 10 reference subjects and 19 patients with cerebral infarction. Mild but significant hyperhomocysteinemia involving total and free homocysteine (but not reduced homocysteine) was found in the patients.
HPLC measurement, blood distribution, and pharmacokinetics of oral clotrimazole, potentially useful antisickling agent
Authors: Rifai N , Sakamoto M , Law T , Platt O , Mikati M , Armsby C C , Brugnara C 
Published: January 2020

Abstract
Clotrimazole (CLT) has recently been shown to be a potent and specific inhibitor of the Ca(2+)-activated K+ channel and to thereby prevent K+ loss and cellular dehydration of sickled erythrocytes. This evidence suggests that oral CLT may be a useful new therapy for sickle cell disease. Here, we describe the development of an HPLC assay to measure CLT, a method we used to study the pharmacokinetics and transport of CLT in normal volunteers. The assay's linear range extended to 10 mumol/L; the detection limit was 0.1 mumol/L, analytical recovery 97.7%, and run-to-run imprecision (CV) &lt; 4.7%. In unaffected subjects, CLT concentration peaked within 6 h of oral administration and returned to close to baseline by 24 h. High-density lipoproteins appear to be the main carriers of this drug in both normo- and hypertriglyceridemic plasma. We conclude that the method described here is ideally suited for therapeutic monitoring of CLT concentrations.
Effect of storage at 4 degrees C and -20 degrees C on lipid, lipoprotein, and apolipoprotein concentrations
Authors: Evans K , Mitcheson J , Laker M F 
Published: January 2020

Abstract
We have investigated the effects on lipid, apolipoprotein, and lipoprotein measurements of storing unfractionated serum at 4 degrees C for 10 days and at -20 degrees C for 10 days or 3 months. Total serum concentrations of lipids were stable, although apolipoprotein B showed a 5.3% increase after 3 months at -20 degrees C (P &lt; 0.001). Increases in low-density (LDL) and high-density lipoprotein (HDL) triglyceride and very-low-density lipoprotein (VLDL) esterified cholesterol concentrations and decreases in free cholesterol concentrations in LDL and HDL after storage of serum for 10 days at 4 degrees C were verified by fractionation of lipoproteins by sequential flotation ultracentrifugation. Ten days' storage of serum at -20 degrees C resulted in increases in VLDL triglyceride and phospholipid concentrations, with decreases in HDL concentrations in triglycerides and phospholipids; changes were more extensive after 3 months at -20 degrees C. We conclude that ultracentrifugation of serum for lipoprotein analysis should be performed as soon as possible after collection.
Robust nonradioactive oligonucleotide ligation assay to detect a common point mutation in the CYP2D6 gene causing abnormal drug metabolism
Authors: Hansen T S , Petersen N E , Iitiä A , Blaabjerg O , Hyltoft-Petersen P , Hørder M 
Published: January 2020

Abstract
A new nonradioactive oligonucleotide ligation assay for the detection of a common point mutation in the CYP2D6 gene is presented. The assay takes advantage of simultaneous time-resolved fluorescence measurements of lanthanide-labeled probes and the specificity of T4-DNA ligase in combination with the polymerase chain reaction. This strategy makes it possible to perform the assay using both the wild-type-specific and mutant-specific probes simultaneously, securing an internal control in each reaction. We show that the allele-specific ligation part of the assay can be performed with great accuracy over a wide range of temperatures, salt concentrations, and T4-DNA ligase concentrations. This eliminates the risk of false-positive or false-negative reactions due to variations in these factors. Because the assay is simple to perform, is very reliable, and can be partly automated, we conclude that it is well-suited for analysis in a routine laboratory.
Restriction fragment length polymorphisms of apolipoprotein B gene in Chinese population with coronary heart disease
Authors: Pan J P , Chiang A N , Tai J J , Wang S P , Chang M S 
Published: January 2020

Abstract
Three restriction fragment length polymorphisms (RFLPs), EcoRI (R), Xbal (X), and Mspl (M) of the apolipoprotein (apo)B gene, were studied to determine their distribution frequencies and influence on the lipid profiles in 148 Chinese patients with documented coronary heart disease (CHD) and in 153 healthy subjects. The plasma concentrations of cholesterol and apoB showed no difference between the CHD patients and controls. However, CHD patients had significantly higher concentrations of low-density lipoprotein cholesterol and triglyceride and lower concentrations of high-density lipoprotein cholesterol than the controls. The frequencies of these three apoB RFLPs did not differ between the CHD patients and controls. Compared with South Asians and Caucasians, the Chinese in Taiwan showed a much lower frequency of R-, X+, and M- alleles. There was no evidence of an association between lipid profiles and RFLPs in either CHD patients or controls. The weak association of EcoRI, Xbal, and Mspl polymorphisms of the apoB gene with CHD indicates that the three RFLPs cannot be used as a predictor for the risk of CHD in the Chinese population.
HPLC with o-phthalaldehyde precolumn derivatization to measure total, oxidized, and protein-bound glutathione in blood, plasma, and tissue
Authors: Paroni R , De Vecchi E , Cighetti G , Arcelloni C , Fermo I , Grossi A , Bonini P 
Published: January 2020

Abstract
This HPLC assay with o-phthalaldehyde precolumn derivatization is used to measure the total, oxidized, and protein-bound forms of glutathione in human blood, plasma, and rat tissue. Total glutathione (i.e., sum of reduced, oxidized, and protein-bound fractions) was determined after reduction with dithiothreitol and protein precipitation with perchloric acid (PCA). A preliminary selective blockage of free sulfhydryl groups with N-ethylmaleimide was necessary to evaluate the different oxidized forms. The assay showed high sensitivity (&lt; 0.05 pmol injected) and good precision (within-day CVs of 5.5% to 6.4%), recovery (101% +/- 4%), and linearity (r &gt; 0.999). Samples, after PCA acidification, were stable at room temperature and 4 degrees C for 3 days, and at -20 degrees C and -80 degrees C for &gt; 1 month. The method (involving automated derivatization) not only is very rapid and simple but also allows immediate processing of many different biological samples.
Enzymatic markers of gallstone-induced pancreatitis identified by ROC curve analysis, discriminant analysis, logistic regression, likelihood ratios, and information theory
Authors: Kazmierczak S C , Catrou P G , Van Lente F 
Published: January 2020

Abstract
We investigated the diagnostic utility of frequent serial determinations of aspartate aminotransferase, alanine aminotransferase (ALT), lipase, amylase, and the lipase/amylase (L/A) ratio for distinguishing patients with acute pancreatitis due to biliary obstruction from those with acute pancreatitis due to other pathogenesis. Analyzed were enzyme activities obtained at admission and peak enzyme activities identified retrospectively from serial measurements in 53 patients with acute pancreatitis due to various causes. We evaluated the data with multiple statistical tools. Discriminant analysis and logistic regression revealed the diagnostic significance of ALT at initial and peak values, and the maximum information provided by peak ALT was confirmed by both logistic regression and stratum-specific likelihood ratios. Stratum-specific likelihood ratios showed peak ALT &gt; 150 U/L was highly diagnostic of biliary pancreatitis. The L/A ratio, either at admission or at peak, was the only other significant variable for identifying patients with acute pancreatitis due to biliary obstruction. A multivariate logistic discriminant function including ALT and the L/A ratio significantly discriminated biliary acute pancreatitis from pancreatitis due to other causes. Evaluation of initial and peak enzyme data by information theory revealed that the optimal test depended on disease prevalence. Initial ALT activities were the test of choice for identifying biliary pancreatitis, up to a disease prevalence of approximately 0.75. At disease prevalence &gt; 0.75, the initial L/A ratio provided the greatest amount of diagnostic information.
Enzyme immunoassay of immunoreactive progastrin-releasing peptide(31-98) as tumor marker for small-cell lung carcinoma: development and evaluation
Authors: Aoyagi K , Miyake Y , Urakami K , Kashiwakuma T , Hasegawa A , Kodama T , Yamaguchi K 
Published: January 2020

Abstract
Previously, using recombinant human progastrin-releasing peptide (ProGRP)(31-98), we developed a RIA for ProGRP(31-98) and demonstrated that the determination of serum ProGRP(31-98) was a reliable marker for small-cell lung carcinoma (SCLC) (Miyake et al., Cancer Res 1994;54:2136-40). Aiming for a more convenient assay system, we have now developed and evaluated a highly sensitive and specific ELISA for ProGRP(31-98). Only 50 microL of nonextracted serum is needed, and results are obtained in only 2 h. Intraassay and between-day CVs were 1.7-4.6% and 4.2-6.8%, respectively. The log-log calibration curve was linear to 1000 ng/L, and analytical recovery was 91.5-108.7%. The detection limit of this assay, 1.9 ng/L, means that basal concentrations of ProGRP(31-98) were detectable in all healthy subjects. The cutoff value, based on the mean + 3 SD of concentrations in 247 healthy subjects, was set to 45.1 ng/L. Serum concentrations exceeded this value in 18 of 25 SCLC patients, similar to the frequency of increased values found by RIA previously. In contrast, the frequency of increased serum ProGRP(31-98) in patients with nonmalignant pulmonary diseases or non-SCLC was quite low: 0% and 5.0%, respectively. Such results may justify a clinical trial for evaluating this ELISA for the diagnosis and monitoring of SCLC patients.
Electrochemical determination of low blood lead concentrations with a disposable carbon microarray electrode
Authors: Feldman B J , D'Alessandro A , Osterloh J D , Hata B H 
Published: January 2020

Abstract
Lead concentrations in blood samples typical of unexposed individuals are determined by using square-wave anodic stripping voltammetry at a disposable 287-element (15-35-microns diameter) carbon microarray electrode. Analysis of a series of low Pb-containing samples (blood [Pb] = 17 to 92 micrograms/L) by standard addition gives good accuracy (average bias vs graphite furnace atomic absorption spectroscopy = -4 micrograms/L) and precision (pooled SD = 7 micrograms/L). The signal/noise ratio is improved by about an order of magnitude over that found at a single carbon disk (10 microns diameter), resulting in a detection limit (for the microarray) of 5 micrograms/L for a 60-s deposition of sample.
Determination of pyridinoline and deoxypyridinoline in urine, with special attention to retaining their stability
Authors: Gerrits M I , Thijssen J H , van Rijn H J 
Published: January 2020

Abstract
Urinary excretion of the pyridinium crosslinks pyridinoline (Pyr) and deoxypyridinoline (Dpyr) is used as a biochemical marker of bone resorption. The present study was undertaken to determine the long-term stability of these compounds in stored urine, using the HPLC method. Systematic investigation of their chemical stability in urine demonstrated that both the free and conjugated forms of Pyr and Dpyr are extremely stable: No significant changes were observed after 6 weeks at -20 degrees C storage (e.g., free Pyr 9.6 +/- 1.2 mumol/mol creatinine (before) and 10.6 +/- 3.2 (after); free Dpyr 2.3 +/- 0.2 mumol/mol creatinine (before) and 2.5 +/- 1.2 (after)). These results predict stability of urines stored for 10-20 years at -20 degrees C in the dark. Also, freezing and thawing as many as 10 times had no effect on the concentrations of the crosslinks. Study of the stability of the excretion pattern in healthy women showed substantially higher variations in excretions of free and total Dpyr (18% and 13%, respectively) than of Pyr (10% for both forms).
Automated measurement of urinary iodine with use of ultraviolet irradiation
Authors: Tsuda K , Namba H , Nomura T , Yokoyama N , Yamashita S , Izumi M , Nagataki S 
Published: January 2020

Abstract
We have modified an automated measurement system of urinary iodine (UI) and established a sensitive UI assay system by using ultraviolet (UV) digestion. The automated system is sensitive enough to detect concentrations of UI &lt; 0.78 mumol/L (&lt; 10 micrograms/dL) in a small volume of urine (500 microL). Sample throughput is &gt; 30/h, including a water washing. The within-assay imprecision (CV) was &lt; or = 10% in the UI range of 0.10-3.00 mumol/L; the between-assay CV was usually &lt; or = 15% in the same range. Analytical recovery of iodine added to urine samples was consistently &gt; 90%. The theoretical values were recovered when UV irradiation was used but not in its absence. High (supraphysiological) doses of thiocyanate or ascorbic acid, which are major interfering substances to the ceric-arsenious acid reaction, did not interfere with this system. The correlation between UI determined by this method and by the acid digestion method was linear (r = 0.994). For samples containing iodine at &lt; 1.00 mumol/L, the correlation between values by both methods was still significant (r = 0.937). UI in an iodine-deficient area in Ukraine, measured by this system, ranged from 0.06 to 1.83 mumol/L (median 0.44 mumol/L, n = 95), significantly lower than in Japan (range 0.23-50.70 mumol/L, median 4.70 mumol/L, n = 84) and consistent with mild iodine deficiency. This modified automated assay system, therefore, is useful and applicable for screening UI in inhabitants of iodine-deficient areas.
Automated homogeneous liposome-based assay system for total complement activity
Authors: Yamamoto S , Kubotsu K , Kida M , Kondo K , Matsuura S , Uchiyama S , Yonekawa O , Kanno T 
Published: January 2020

Abstract
We developed an automated homogeneous immunoassay, based on immune lysis of dinitrophenyl (DNP)-labeled liposomes, for measuring total complement activity. Liposome lysis caused by complement activity was detected spectrophotometrically from entrapped glucose-6-phosphate dehydrogenase activity. Complement activity in human sera was quantified by comparison with a calibration curve. For ease of application to fully automated routine clinical analyzers, we adopted a two-reagent system, one reagent containing a homogeneous population of small DNP-labeled liposomes and one containing antibody/substrate. This system required calibration only once a week. Within-run and between-run CVs were 0.4-1.3% (n = 10) and 1.8-4.7% (n = 10), respectively. Serum results were linear upon dilution (with saline) over a twofold range. Bilirubin, hemoglobin, Intrafat, and serum proteins such as rheumatoid factor, M protein, IgG, and IgA did not affect the assay results. The results (y) correlated well with those from a hemolytic complement activity test (x): y = 1.05x - 1.14, r = 0.92, on 66 samples in the range &lt; 10- &gt; 50 kU/L. This method should therefore be of great use for the determination of complement activity.
Elimination of paraprotein interference in determination of plasma inorganic phosphate by ammonium molybdate method
Authors: Zaman Z , Sneyers L , Van Orshoven A , Blanckaert N , Mariën G 
Published: January 2020

Abstract
Phosphate concentrations were determined in 52 cases of paraproteinemia. The unmodified acidic ammonium molybdate method produced 19% spuriously high results. The false increase of phosphate concentration was attributable to formation of precipitate in the reaction mixture. The precipitate was formed by interaction between immunoglobulins and the unmodified acidic ammonium molybdate reagent. The magnitude of interference bore no relation to the type, concentrations, or isoelectric point of the paraproteins or to the presence or absence of free light chains. Diluting the sample to approximately 40 g/L total protein reduced but did not always eliminate the interference. In some cases paraprotein concentration as low as 8 g/L falsely increased plasma phosphate results. Apparently, only IgG and IgM but not IgA paraproteins produced the interference. Deproteination by ultrafiltration or by treatment with trichloroacetic acid removed the interference. The Kodak slide method and the new modified Boehringer Mannheim phosphate test were found to be interference-free. However, in some cases the latter new formulation is sensitive to substantial changes in ionic concentration of the reaction mixture.
Pseudo-pseudohypertriglyceridemia: a case of increased free glycerol without evidence for glycerol kinase deficiency
Authors: Nauck M , Winkler K , Siekmeier R , Marangos N , Richter B , März W , Wieland H 
Published: January 2020

Abstract
High concentrations of glycerol in plasma may result in overestimation of triglycerides in chemical and enzymatic assays. Known causes of increased glycerol concentrations in blood include glycerol-contaminated blood-collector tubes and pseudohypertriglyceridemia, a condition caused by genetic defects in the gene for glycerol kinase. We report a patient with sudden hearing loss who presented with an increased blood glycerol concentration after undergoing an oral glycerol test.
Bone alkaline phosphatase and height velocity in short normal children undergoing growth-promoting treatments: longitudinal study
Authors: Crofton P M , Stirling H F , Kelnar C J 
Published: January 2020

Abstract
We studied the temporal and quantitative relation between bone alkaline phosphatase (ALP) and height velocity in 62 short normal children as part of a prospective randomized study to compare placebo, growth hormone, oxandralone, and testosterone, singly and in combination, in promoting short-term growth acceleration and increased final height. The pretreatment cross-sectional correlation between bone ALP and height velocity was poor (P &gt; or = 0.25), but was much higher (P = 0.0001) 3 months after treatment started. In each treatment group, there was a parallel relation between bone ALP and height velocity through time. Individual children showed a variety of growth responses over 12-42 months, but in almost all cases bone ALP paralleled height velocity. Within individual children, bone ALP was strongly correlated with 6-month height velocity (r &gt; 0.9 in 30% of the children, r &gt; 0.7 in 70%). We conclude that bone ALP is a useful short-term marker of growth in short normal children treated with growth hormone.
Validation of allele-specific polymerase chain reaction for DNA typing of HLA-B27
Authors: Steffens-Nakken H M , Zwart G , van den Bergh F A 
Published: January 2020

Abstract
To find a specific method for HLA-B27 typing for the diagnosis of rheumatic disorders, we extensively tested the single-step B27-specific polymerase chain reaction (PCR) described by Dominguez et al. (Immunogenetics 1992;36:277-82). This method, which relies on specific primer recognition of a sequence in the third exon (unique to the B27-allele), was used for screening of 270 characterized blood samples, 57 of which were B27-positive. The method proved to be both sensitive and specific: It unambiguously identified all B27-positive samples and produced no false-positive results. For approximately 1% of the samples, we had to repeat DNA isolation and PCR to obtain a clear control amplification signal. In contrast to the specificity of the PCR method, parallel-performed flow cytometry gave ambiguous results in 3% of the samples because of antibody cross-reactivity. Flow cytometry and the PCR method described were similar in labor and costs. Therefore, we conclude that the proposed single-step PCR is feasible in a routine laboratory and would improve the reliability of HLA-B27 typing.
Prevalence of serum antithyroid peroxidase antibodies in 85-year-old women and men
Authors: Sundbeck G , Edén S , Jagenburg R , Lundberg P A , Lindstedt G 
Published: January 2020

Abstract
Antithyroid peroxidase antibodies (TPOAb) were determined by competitive radioassay in serum samples obtained from a representative population of 85-year-olds (601 women and 285 men). The prevalence of increased TPOAb concentration was significantly higher in the women. In individuals without previously known thyroid dysfunction, 16% of the women and 9% of the men had TPOAb concentration &gt; 100 kilo-units/L, the upper decision limit. We found a direct relationship between TPOAb and thyrotropin (TSH) concentrations and an inverse relationship between TPOAb and free thyroxine (T4) concentrations, but no relationship between TPOAb and defined disorders or treatment with pharmaceutical drugs. Exclusion of individuals with increased TPOAb concentration and conditions influencing TSH and free T4 concentrations resulted in a decrease of the upper reference limit for TSH concentration and an increase of the lower limit for free T4 concentration, indicating that high TPOAb concentration should be taken into account when evaluating normal reference intervals for thyroid-function tests in the elderly.
Direct measurement of high-density lipoprotein cholesterol in serum with polyethylene glycol-modified enzymes and sulfated alpha-cyclodextrin
Authors: Sugiuchi H , Uji Y , Okabe H , Irie T , Uekama K , Kayahara N , Miyauchi K 
Published: January 2020

Abstract
We have developed an automated method for measuring high-density lipoprotein (HDL)-cholesterol in serum without prior separation, using polyethylene glycol (PEG)-modified enzymes and sulfated alpha-cyclodextrin. When cholesterol esterase and cholesterol oxidase enzymes were modified with PEG, they showed selective catalytic activities towards lipoprotein fractions, with the reactivity increasing in the order: low-density lipoprotein &lt; very-low-density lipoprotein approximately chylomicron &lt; HDL. In the presence of magnesium ions, alpha-cyclodextrin sulfate reduced the reactivity of cholesterol, especially in chylomicrons and very-low-density lipoprotein, without the need for precipitation of those lipoprotein fractions. The combination of PEG-modified enzymes with alpha-cyclodextrin sulfate provided selectivity for the determination of HDL-cholesterol in serum in the presence of a small amount of dextran sulfate without the need for precipitation of lipoprotein aggregates. The results of the HDL-cholesterol assayed in serum by this direct method correlated well with those obtained by precipitation-based methods and also that by an ultracentrifugation method.