bluuebunny/crossref_metadata_2025_split huggingface dataset:
Artificial neural network predictions of urinary calculus compositions analyzed with infrared spectroscopy
Authors: Volmer M , Wolthers B G , Metting H J , de Haan T H , Coenegracht P M , van der Slik W 
Published: January 2020

Abstract
Infrared (IR) spectroscopy is used to analyze urinary calculus (renal stone) constituents. However, interpretation of IR spectra for quantifying urinary calculus constituents in mixtures is difficult, requiring expert knowledge by trained technicians. In our laboratory IR spectra of unknown calculi are compared with references spectra in a computerized library search of 235 reference spectra from various mixtures of constituents in different proportions, followed by visual interpretation of band intensities for more precise semiquantitative determination of the composition. To minimize the need for this last step, we tested artificial neural network models for detecting the most frequently occurring compositions of urinary calculi. Using constrained mixture designs, we prepared various samples containing ammonium hydrogen urate, brushite, carbonate apatite, cystine, struvite, uric acid, weddellite, and whewellite for use as a training set. We assayed known artificial mixtures as well as selected patients' samples from which the semiquantitative compositions were determined by computerized library search followed by visual interpretation. Neural network analysis was more accurate than the library search and required less expert knowledge because careful visual inspection of the band intensities could be omitted. We conclude that neural networks are promising tools for routine quantification of urinary calculus compositions and for other related types of analyses in the clinical laboratory.
Quantification of apolipoprotein A-IV in human plasma by immunonephelometry
Authors: Schwarz S , Haas B , Luley C , Schäfer J R , Steinmetz A 
Published: January 2020

Abstract
We developed a nephelometric procedure for determining concentrations of human plasma apolipoprotein (apo) A-IV. Results obtained correlate well with those measured by an established electroimmunodiffusion assay (r = 0.98; n = 56). Intra- and interassay CVs were 2.4% and 2.0%, respectively, indicating excellent precision and reproducibility. Various conditions of sample treatment, such as adequate storage, freezing, and thawing, did not affect results significantly. However, keeping samples at room temperature for 4 days led to a slight increase in measured values. Preincubation with a cholesterinesterase-detergent mixture abolished interference from triglyceride-rich lipoproteins, allowing assay of samples containing triglycerides as great as 10 g/L. The assay is easily applicable to clinical laboratories for routine diagnostic use, as shown with hypertriglyceridemic plasmas and samples with a broad range of apo A-IV concentrations.
Multicenter evaluation of automated immunoturbidimetric assays for measurement of apolipoproteins A-I and B in serum and plasma
Authors: Kahn S E , Labbé R F , Pfadenhauer E H , Kanonchoff A D , Joseph R T 
Published: January 2020

Abstract
Results of a multicenter evaluation of automated assays for measurement of apolipoproteins (apo) A-I and B with the Paramax analytical system are reported. Apo A-I and apo B response surface models were used to optimize concentrations of critical assay variables. Overall imprecision for apo A-I controls at concentrations of 1.01-1.61 g/L was 3.7-6.6%; overall imprecision for apo B controls at 1.00-1.61 g/L was 2.8-6.9%. There was no interference in apo A-I measurements. Albumin concentrations &gt; 59 g/L resulted in a negative interference, and collection in sodium heparin caused a positive interference in apo B results. Apo A-I and apo B assays demonstrated acceptable agreement with comparative methods, although the Paramax apo B assays had a negative bias with respect to comparison methods. In 116 healthy individuals, serum apo A-I ranged from 0.97 to 2.05 g/L and serum apo B ranged from 0.51 to 1.32 g/L.
Improved determination of small amounts of free hydroxyproline in biological fluids
Authors: Lange M , Mályusz M 
Published: January 2020

Abstract
A fast, reliable, and sensitive (&lt; 20 pmol) method for the quantification of 4-hydroxyproline is described. It ensures good separation of imino acid peaks, eliminates interference by primary amino acids, and guarantees full (96-105%) recovery of hydroxyproline (HYP). Interfering primary amino acids are derivatized by o-phthaldialdehyde and removed from the sample by use of a discardable C18 column. HYP is measured photometrically at 254 nm after a second derivatization with phenylisothiocyanate and isocratic separation on a reversed-phase HPLC column.
Quantification of skeletal alkaline phosphatase in osteoporotic serum by wheat germ agglutinin precipitation, heat inactivation, and a two-site immunoradiometric assay
Authors: Farley J R , Hall S L , Ilacas D , Orcutt C , Miller B E , Hill C S , Baylink D J 
Published: January 2020

Abstract
Three methods for quantifying skeletal alkaline phosphatase (ALP; EC 3.1.3.1) activity/immunoactivity in serum--heat inactivation, wheat germ agglutinin (WGA) precipitation, and an immunoradiometric assay--were tested for recovery and specificity and applied to 81 sera collected from 14 postmenopausal osteoporotic subjects. The heat-inactivation and WGA precipitation assays showed relative recoveries of 91-100% and 16-32%, respectively, for skeletal ALP with complete specificity (no cross-reactivity with hepatic or intestinal ALP); the IRMA showed a relative recovery of 86-100% and 11-14% cross-reactivity with hepatic ALP. There was a closer correlation between the heat-inactivation assay and IRMA (r = 0.833) than between the WGA precipitation assay and IRMA (r = 0.673) or between the heat-inactivation and WGA-precipitation assays (r = 0.568). The WGA precipitation assay failed to detect skeletal ALP in three serum samples that contained significant amounts as determined by the heat-inactivation assay and the IRMA.
Microfabrication in silicon microphysiometry
Authors: Baxter G T , Bousse L J , Dawes T D , Libby J M , Modlin D N , Owicki J C , Parce J W 
Published: January 2020

Abstract
Over the past 5 years, microphysiometry has proved an effective means for detecting physiological changes in cultured cells, particularly as a functional assay for the activation of many cellular receptors. To demonstrate the clinical relevance of this method, we have used it to detect bacterial antibiotic sensitivity and to discriminate between bacteriostatic and bacteriocidal concentrations. The light-addressable potentiometric sensor, upon which microphysiometry is based, is well suited for structural manipulations based on photolithography and micromachining, and we have begun to take advantage of this capability. We present results from a research instrument with eight separate assay channels on a 5-cm2 chip. We discuss the planned evolution of the technology toward high-through-put instruments and instruments capable of performing single-cell measurements.
PCR in a silicon microstructure
Authors: Wilding P , Shoffner M A , Kricka L J 
Published: January 2020

Abstract
Devices for performing polymerase chain reactions (PCR) have been developed for use with photolithographed silicon. Microchambers capable of holding between 5.0 and 10 microL of PCR reagents were constructed by etching specific areas of rectangular silicon chips (17 x 15 mm), which were then capped with Pyrex glass. These silicon devices (PCRChips), which were etched to depths of 40-80 microns, permitted free flow of fluids in the microchannels and microchambers. Access to the microchambers was through holes in the silicon. Thermal cycling of the PCR reagents was achieved by placing the disposable PCRChip in a small holder containing a computer-controlled Peltier heater-cooler. Successful amplification was demonstrated by electrophoresis of products in agarose gel containing ethidium bromide, and the migration of the product was compared with that obtained in a commercially available thermal cycler. The thermal characteristics of the silicon, coupled with the high surface area to volume ratio in the new devices, are particularly advantageous features for amplification by PCR.
Feasibility studies for simultaneous immunochemical multianalyte drug assay by capillary electrophoresis with laser-induced fluorescence
Authors: Chen F T , Evangelista R A 
Published: January 2020

Abstract
We present a method for the simultaneous quantification of multiple drug analytes in urine, based on combining immunochemical binding with capillary electrophoretic separation. Two fluorescent drug-cyanine (Cy) dye conjugates were prepared as competing species for the immunoassay. Morphine was derivatized with Cy5 (lambda max = 652 nm, epsilon = 215,000 mol-1cm-1 L), phencyclidine (PCP) with Cy5.5 (lambda max = 675 nm, epsilon = 200,000 mol-1cm-1L). The high-efficiency resolving power of the capillary electrophoresis system (20 microns x 27 cm column) separated the individual labeled drugs, and the antigen-antibody complexes were detected by laser-induced fluorescence (laser: 10 mW He-Ne at 632.8 nm) with Cy5 diacid as internal standard. Simultaneous competitive immunoassay of morphine and PCP in urine showed that the free labeled-drug peak areas were proportional to the concentrations of the drug species present in the urine sample. This immunoassay can be performed routinely and reproducibly in &lt; 5 min with analytical detection limits of 4 nmol/L for PCP and 40 nmol/L for morphine.
Role of low-density lipoproteins in atherogenesis and development of coronary heart disease
Authors: Grundy S M 
Published: January 2020

Abstract
There is a strong association between increased blood concentrations of low-density lipoprotein (LDL) and severity of coronary atherosclerosis. Multiple mechanisms affect hypercholesterolemia, e.g., diet, aging, hormones, and genetics. LDL receptors apparently are also important--through down-regulation, defects in structure, or decreased numbers--as are changes in LDL binding characteristics caused by alterations in apolipoprotein B content or structure. Current concepts of LDL metabolism are extensively reviewed, including the role of modified or oxidized LDL in atherogenesis.
Serum apolipoproteins A-I and B as markers of coronary artery disease risk in early life: the Bogalusa Heart Study
Authors: Srinivasan S R , Berenson G S 
Published: January 2020

Abstract
The functional properties of the apolipoproteins (apoB and apoA-I) governing lipoprotein metabolism make these variables conceptually important as markers for coronary artery disease risk. This aspect was examined in a biracial (black-white) population of children as part of the Bogalusa Heart Study. White children, especially boys, showed lower concentrations of apoA-I and ratios of cholesterol to apoB within low-density lipoprotein (LDL) than did black children. Persistence of apoB concentrations over time, coupled with its strong linkage with apoB gene locus, underscores the value of detecting apoB excess early in life. Further, the impact of apoE genotypes on apoB and apoA-I levels is already evident in childhood. We found that, as a screening test for detecting increased LDL cholesterol, apoB is superior to total cholesterol. Low values for apoA-I concentration, the apoA-I to apoB ratio, and LDL cholesterol to apoB ratio in children are strongly related to parental incidence of myocardial infarction; no such relationship is seen with respect to lipoprotein cholesterols. Thus, expanding screening strategies might be useful for identifying individuals with adverse apolipoprotein profiles early in life.
Relation of high-density lipoprotein subfractions and apolipoprotein E isoforms to coronary disease
Authors: Wilson P W 
Published: January 2020

Abstract
Although a variety of methods have become available for the determination of high-density lipoprotein (HDL) subfractions in plasma, a review of published data from nine studies of coronary disease outcomes and 10 investigations of coronary artery disease severity do no suggest that measurement of HDL2-cholesterol (C) and HDL3-C offer any advantage in the prediction of coronary disease over the determination of total HDL-C alone. Apolipoprotein E is typically present in plasma as one of six isoforms, the six being encoded by three common alleles, epsilon 2, epsilon 3, and epsilon 4. The epsilon 3 allele is the most common, the epsilon 4 allele has been reported to be associated with higher cholesterol concentrations, and the epsilon 2 and epsilon 4 alleles are both associated with higher triglyceride concentrations. Clinical and arteriographic studies of coronary disease suggest that vascular disease risk is increased among persons with the epsilon 4 allele.
Multicenter evaluation of enhanced chemiluminescence labeled-antibody immunoassay (Amerlite-MAB) for free thyroxine
Authors: Christofides N D , Sheehan C P 
Published: January 2020

Abstract
The technical and diagnostic performance of the Amerlite-MAB enhanced luminescence assay for free thyroxine (FT4) was assessed in a multicenter evaluation trial. The euthyroid central 95% reference range for FT4 (1393 subjects) was 11.5-27.7 pmol/L (by cumulative frequency plot with two-tailed 2.5% cutoffs). Results (y) agreed with those of similar radioactive method (Amerlex-MAB FT4) (x): y = 1.06 x + 0.54, Sylx = 335.5, n = 235). Mean within-assay precision (CV) in six centers was 5.7% at 6 pmol/L and 2.6% at 51 pmol/L FT4; between-assay precision (CV) was 7.2% and 3.6%, respectively. Diagnostic performance was assessed in all patient groups usually encountered, including those with nonthyroidal illness and extreme binding-protein anomalies. In elderly euthyroid subjects, the proportion of above-normal FT4 values exceeded that in younger age-groups. These increases often accompanied normal estimates of thyrotropin and, in some cases, might have arisen by interference from medication that is taken more often by the elderly.
Indirect estimation of thyroid hormone-binding proteins to calculate free thyroxine index: comparison of nonisotopic methods that use labeled thyroxine ("T-uptake")
Authors: Faix J D , Rosen H N , Velazquez F R 
Published: January 2020

Abstract
There are many alternative ways of estimating free thyroxine (T4) when thyrotropin screening results are abnormal. In addition to free T4 immunoassays, the menu of most automated immunoassay instruments includes a nonisotopic version of the original triiodothyronine (T3)-uptake assay called "T-uptake." We evaluated the ability of five such assays (Access, ES-300, IMx, Magnum Opus, and Stratus) to accurately estimate the free thyroxine index (FTI) in euthyroid, hyperthyroid, and hypothyroid patients with abnormal concentrations of thyroid hormone-binding proteins, and in patients with nonthyroidal illness. For comparison, we calculated a similar FTI, using either T3-uptake or direct measurement of thyroxine-binding globulin (TBG). Euthyroid reference ranges were comparable. Of euthyroid patients with increased TBG, 12-32% and 5-20% had increased or suppressed FTI, respectively, depending on the T-uptake method used. Except for IMx, 6-35% of hypothyroid patients with increased TBG had inappropriately increased FTI. Patients with nonthyroidal illness had comparable results regardless of the method used, and T-uptake methods were variably affected by known inhibitors of thyroid hormone binding. The most reliable T-uptake method appeared to be the IMx, which, despite claims that it measures all thyroid hormone-binding proteins, correlated best with TBG concentrations.
Apolipoprotein E2/E3/E4 genotyping with agarose gels
Authors: Dallinga-Thie G M , van Linde-Sibenius Trip M , Kock L A , De Bruin T W 
Published: January 2020

Abstract
Here we report an improved, simple method to assign the human apolipoprotein (apo) E genotype and its isoforms, apo E2, apo E3, and apo E4. Genomic DNA was amplified with specific primers that included the polymorphic region of amino acids 112 and 158. Digestion of the product with Hhal resulted in unique fragments that were separated on Meta-Phor agarose instead of polyacrylamide. The pattern of unique DNA fragments obtained unequivocally characterizes the different apo E alleles.
Direct solid-phase sequence analysis of the human p53 gene by use of multiplex polymerase chain reaction and alpha-thiotriphosphate nucleotides
Authors: Berg C , Hedrum A , Holmberg A , Pontén F , Uhlén M , Lundeberg J 
Published: January 2020

Abstract
Among the candidate cancer-prognostic genes is the p53 tumor suppressor gene, which, when mutated, plays an important role in the development of many types of cancers. To facilitate robust large-scale DNA analysis of microdissected tumor biopsies, we describe a multiplex/nested PCR approach for a simultaneous outer amplification of exons 4-9 of the human p53 gene with parallel amplification of the HLA-DQB1 locus, involving a total of 14 primers. This approach reduces the required number of cells for analysis and avoids any variation in the amplifications of the individual p53 exons during the common outer amplification step. The HLA sequencing allows sample identification because the DQB1 locus is highly polymorphic and is thereby patient-specific. The p53 and HLA amplicons are analyzed by solid-phase sequencing in a semiautomated format. To improve the DNA sequence quality, we used 2'-deoxyribonucleoside 5'-O-1-thiotriphosphates in the sequencing reactions.
Cholesterol content of circulating immune complexes in patients with coronary stenosis and subjects without evidence of atherosclerosis
Authors: Lecomte E , Herbeth B , Clerc G , Khalife K , Siest G , Artur Y 
Published: January 2020

Abstract
The biological variation factors for cholesterol in circulating immune complexes (CIC-cholesterol) were studied in 941 unselected supposedly healthy volunteers, ages 4 to 78 years. We found a complex effect of age, including the existence of two peaks of CIC-cholesterol, one in males between 11 and 14 years and in females between 11 and 30 years, and in both sexes another peak between 41 and 60 years, and in both sexes a decrease between 31 and 40 years. By use of multiple regression analysis and after adjustment for age, CIC-cholesterol was positively related to plasma cholesterol concentration and leukocyte count, values being lower in females than in males and among subjects taking anti-inflammatory drugs. In addition, CIC-cholesterol was measured in 76 coronary angiography patients and in 100 supposedly healthy controls, ages 30 to 77 years. We noticed a significant increase (P &lt; or = 0.05) of CIC-cholesterol when patients were affected by coronary stenosis between 20% and 50% (71.8 +/- 52.5 mumol/L vs 46.2 +/- 45.9 mumol/L in controls), but this was less pronounced in those with &gt; 50% of obstruction (58.9 +/- 54.3 mumol/L); however, serum total cholesterol was not modified or even surprisingly slightly decreased in the coronary angiography individuals. Nevertheless, an important overlap of values in controls and patients makes questionable the usefulness of this variable in clinical practice.
Improved RNase protection assay for quantifying LDL-receptor mRNA; estimation of analytical imprecision and biological variance in peripheral blood mononuclear cells
Authors: Petersen N E , Larsen L K , Nissen H , Jensen L G , Jensen A , Hyltoft Petersen P , Hørder  , Gregersen N , Kristiansen K 
Published: January 2020

Abstract
We have improved the protocol for RNA quantification by using RNase protection. Instead of precipitation and extraction with phenol and chloroform, we use a faster and more reliable precipitation based on guanidinium thiocyanate (GdSCN). The internal standard is produced by in vitro transcription of a DNA template constructed so as to allow simultaneous detection of the in vitro transcript and the low-density lipoprotein receptor (LDLR) mRNA by use of the same probe and hybridization. Addition of this internal standard at the step for RNA isolation reduced the analytical imprecision from 40.8% to 19.3%. Estimates of the within- and between-subject biological variations of the LDLR mRNA content in peripheral blood mononuclear cells (PBMCs) isolated from healthy volunteers were 21.5% and 13.6%, respectively, and the analytical imprecision was 22.6%. The mean content of LDLR mRNA in PBMCs from healthy individuals was 0.78 copies per cell.
Proposed confirmatory procedure for detecting 5 alpha-dihydrotestosterone doping in male athletes
Authors: Kicman A T , Coutts S B , Walker C J , Cowan D A 
Published: January 2020

Abstract
Currently, there is no recommended confirmatory procedure for detecting doping with the anabolic steroid 5 alpha-dihydrotestosterone (DHT) in sportsmen. To develop a method, we determined ratios of hormone concentrations in urine from 120 healthy men and used these to set discrimination limits. These limits were then applied to results for urine specimens from 10 volunteers given DHT percutaneously (125 mg twice daily for 4 days). The ratio of DHT to epitestosterone (EpiT) was chosen as the primary marker of DHT administration, and ratios of 5 alpha-androstane-3 alpha, 17 beta-diol (5 alpha-ADIOL) to EpiT, 5 alpha-ADIOL to luteinizing hormone, and 5 alpha-ADIOL to 5 beta-androstane-3 alpha, 17 beta-diol were proposed as secondary markers. To evaluate method suitability, we analyzed 194 samples from sports competitors; results for 193 samples were negative, but the ratios in 1 sample greatly exceeded all the chosen limits. In conclusion, we propose that a test scheme based on our recommendations be considered for implementation in all Olympic drug-testing laboratories.
Glycohemoglobin assays evaluated in a large-scale quality-control survey
Authors: Gillery P , Labbé D , Dumont G , Vassault A 
Published: January 2020

Abstract
We report the results of a national quality-control survey on glycohemoglobin (GHb), monitored in France by the Société Française de Biologie Clinique on behalf of the authority of the "Agence du Médicament." A sample of lyophilized hemolysate was sent to 3109 laboratories. Results were obtained from 2770 laboratories. HbA1C, HbA1, and total GHb were measured by 50%, 24%, and 26% of the participants, respectively. Of these measurements, 79% of the HbA1C results and 76% of the total GHb results, but only 48% of the HbA1 results, were within the +/- 20% limits of the indicated target values. Mean values for the hemolysate ranged from 8% to 11% for HbA1C, from 7% to 12% for HbA1, and from 11% to 13% for total GHb. The interlaboratory CVs ranged from 3% to 20%, according to method used. So, methods used for GHb assay, which are based on various principles, exhibit very different analytical performances. Nonetheless, this large-scale study indicates that some techniques can support transferability of results from laboratory to laboratory.