bluuebunny/crossref_metadata_2025_split huggingface dataset:
Colorimetric assay of glycoprotein glycation free of interference from glycosylation residues
Authors: Kennedy D M , Skillen A W , Self C H 
Published: January 2020

Abstract
We have developed a colorimetric assay for determining the degree of glycation of serum proteins that is unaffected by glycosylation residues. This was accomplished by reducing the proteins with sodium borohydride prior to periodate oxidation. Previous periodate-based methods, which offer several advantages over other glycation assays, cannot determine glycoprotein glycation because interference from sialic residues in the glycan chain can lead to overestimation of the amount of glycation products. Without reduction, glycation of fetuin was double that of asialofetuin glycated under identical conditions. We found that borohydride reduction before periodate oxidation increases the amount of formaldehyde released in proportion to the extent of glycation, irrespective of the degree of glycosylation. Using two glycoproteins and an unglycosylated protein, we showed how measurement of the formaldehyde increase enables the extent of glycoprotein glycation to be determined without removal of interfering sugars.
Nonradioactive, colorimetric microplate hybridization assay for detecting amplified human immunodeficiency virus DNA
Authors: Rapier J M , Villamarzo Y , Schochetman G , Ou C Y , Brakel C L , Donegan J , Maltzman W , Lee S , Kirtikar D , Gatica D 
Published: January 2020

Abstract
A nonradioactive, colorimetric microplate hybridization procedure was used to assay human immunodeficiency virus (HIV) DNA, amplified by the polymerase chain reaction (PCR). Under the PCR conditions used, four proviral copies per 150,000 cells were detected by amplifying a series of DNA mixtures that contained various copy numbers of HIV. Assays of PCR-amplified DNA from peripheral blood mononuclear cells of seronegative individuals yielded negative results (104 of 104), whereas samples from seropositive individuals yielded &gt; 99% positive results (141 of 142). Similar results were obtained in a chemiluminescent assay with an acridinium ester-labeled probe and in a solution hybridization assay in which a 32P-labeled probe was used.
Hapten-heterologous conjugates evaluated for application to free thyroxine immunoassays
Authors: Khosravi M J , Papanastasiou-Diamandi A 
Published: January 2020

Abstract
We evaluated the effect of hapten heterology on free thyroxine (FT4) immunoassays involving the biotin-streptavidin system and time-resolved fluorometry. We compared protein derivatives of thyroxine (T4) and triiodothyronine (T3) as solid-phase antigen or biotinylated protein-tracer conjugate for competitive (or sequential) binding to a mouse anti-T4 monoclonal antibody. In both one- and two-step assays, the heterologous combination of the antibody and T3 conjugates showed superior standard curve sensitivity but up to eightfold lower zero standard signal (B(o)) when the same amounts of antibody and conjugates were used. The improved sensitivity was not altered when the amount of coupled T3 was increased to obtain a B(o) value similar to that of the homologous combination of antibody and T4 conjugates. In the two-step format, the sensitivity of the homologous assay was insufficient for routine use, consistent with displacement of bound T4 during the antibody back-titration step (demonstrated in the T4 displacement experiment with excess conjugate). Results from the one-step (labeled antibody) heterologous assay for approximately 85 clinical samples correlated well with those from an immunofluorometric assay and a two-step radioimmunoassay. The assay was not affected by a wide variation in endogenous serum concentrations of T4-binding globulin and albumin.
Selective removal of beta 2-microglobulin from plasma specimens of long-term hemodialysis patients by high-performance immunoaffinity chromatography
Authors: Mogi M , Harada M , Kojima K , Adachi T , Nakamura S 
Published: January 2020

Abstract
We examined the suitability of high-performance immunoaffinity chromatography (HPIAC) for removing beta 2-microglobulin (beta 2-MG) from plasma of patients (n = 26) undergoing long-term hemodialysis. We used immobilized antibody to beta 2-MG to prepare an immunoaffinity column with a 0.5-mL bed volume. Plasma samples of 0.5 mL were chromatographed at a flow rate of 0.5 mL/min and pressures &lt; 7 kg/cm2. Although only a small amount of beta 2-MG can be removed with a conventional dialyzer, 92.1% +/- 0.4% of the globulin could be removed by HPIAC. The column could be reused after acid elution. After 50 cycles the efficiency of beta 2-MG trapping was 73% of the original efficiency.
Time-resolved immunofluorometric assay of complement C3: application to cerebrospinal fluid
Authors: Gaillard O , Meillet D , Diemert M C , Musset L , Delattre J , Schuller E , Galli J 
Published: January 2020

Abstract
Complement components have a role in various neurological disorders. Complement C3 can be measured by immunochemical methods, but only radioimmunoassays and electroimmunodiffusion assays (EIDs) are sufficiently sensitive to be applied to biological fluids in which the C3 concentration is low, especially cerebrospinal fluid (CSF). We report a sandwich-type time-resolved immunofluorometric assay (TR-IFMA) for C3 in CSF. The linearity (0.7-3650 micrograms/L) and intra- (CV &lt; 4.8%) and inter-assay (CV &lt; 10.9%) precision were satisfactory and the results agreed with those of EID. The assay is extremely sensitive (&lt; 1 microgram/L) and its analytical range is large and well suited to clinical applications. This simple TR-IFMA is thus a nonisotopic alternative to radioimmunoassay for the quantification of complement C3 in CSF.
Clinical measurement of serum amiodarone and desethylamiodarone by using solid-phase extraction followed by HPLC with a high-carbon reversed-phase column
Authors: Jandreski M A , Vanderslice W E 
Published: January 2020

Abstract
We describe a rapid, simple HPLC method routinely used in our clinical laboratory for determining amiodarone and its metabolite desethylamiodarone. These compounds are released from serum proteins by pretreatment with an acidic solution and then extracted onto a C2 reversed-phase clean-up column. After elution from the extraction column, the compounds are separated and quantified by HPLC with a C18 reversed-phase column and spectrophotometric detection. The standard curves for the drug and metabolite are linear up to 20.0 mg/L, with a lower limit of detection of 0.16 mg/L. The CVs for intra-assay precision were 5.0% at 0.58 mg/L and 2.9% at 5.96 mg/L; for inter-assay precision, they were 9.6% at 0.52 mg/L and 6.1% at 2.09 mg/L. Lipemia, hemoglobin, and bilirubin up to 300 mg/L do not interfere with this assay. None of &gt; 550 cardiac patients' samples tested contained a compound that interferes with this assay.
Rapid determination of erythrocyte pyruvate kinase activity
Authors: Mosca A , Tagarelli A , Paleari R , Scarpelli P , Brancati C 
Published: January 2020

Abstract
We report a new potentiometric method for determining pyruvate kinase (PK). Enzymatic activity is measured by monitoring the change in pH produced in the reaction buffer under International Committee for Standardization in Haematology (ICSH) standardized assay conditions, and the lactate dehydrogenase reaction is automatically subtracted in each measuring cycle. The analysis, performed at 37 degrees C, requires a 10-microL sample (isolated erythrocytes or whole blood) and is completed in 2.5 min. The intra-assay CV is &lt; 4% (PK between 3 and 35 U/g Hb); the interassay CV is 4.0% (PK 15 U/g Hb); results are linear from 3 to 30 U/g Hb. A good correlation with the ICSH reference method (x) was found: y = 1.011x - 0.05; n = 32; r = 0.9939; Sylx = 0.75 (units: U/g Hb). The reference intervals of the PK activity in isolated erythrocytes (RBC-PK) were estimated in 89 normal subjects. We found that women possess a higher RBC-PK than do men (P &lt; 0.0001) and that the biological variability (CVb) of RBC-PK is 13.5%. Applications of the proposed method to the hematological routine are reported.
Increased urinary excretion of pyridinium cross-links in cancer patients
Authors: Lipton A , Demers L , Daniloff Y , Curley E , Hamilton C , Harvey H , Witters L , Seaman J , Van der Giessen R , Seyedin S 
Published: January 2020

Abstract
Pyridinoline (PYD) and deoxypyridinoline (DPD), two collagen-based cross-links found in bone, were measured by high-performance liquid chromatography in urine samples from 65 control subjects and 97 patients with either untreated or progressive cancer. Patients with cancer had significantly (P &lt; 0.001) higher urine concentrations of PYD and DPD than did control subjects. Both cross-links were increased in cancer patients with and without clinically detectable bone metastases, although patients with bone and liver involvement had higher mean concentrations. The mean concentrations of both cross-links were also significantly higher in the urine samples of inpatients than in an outpatient ambulatory population. These findings suggest that the measurement of PYD and DPD in urine may be useful in assessing bone metastases and bone resorption in cancer patients.
Measurement of heroin and its metabolites by isotope-dilution electron-impact mass spectrometry
Authors: Goldberger B A , Darwin W D , Grant T M , Allen A C , Caplan Y H , Cone E J 
Published: January 2020

Abstract
A solid-phase extraction procedure was developed for the isolation of heroin, 6-acetylmorphine, and morphine from blood, plasma, saliva, and urine with subsequent assay by gas chromatography/mass spectrometry. Aprotic solvents, mild elution conditions, and an enzyme inhibitor were used to ensure maximum analyte stability. Samples were extracted and the extract was divided into two equal portions. One portion was assayed directly for heroin; detector response was linear over a concentration range of 1.0 to 250 micrograms/L. The second part of the extract was reacted with N-methyl-bis-trifluoroacetamide and assayed for the trifluoroacetyl derivatives of 6-acetylmorphine and morphine; detector response was linear over a concentration range of 1.0 to 500 micrograms/L. The limit of sensitivity was 1.0 microgram/L for each analyte. Hydrolysis of heroin to 6-acetylmorphine during extraction and analysis was &lt; 5%. The method can be used to corroborate heroin use and to study the pharmacological effects of heroin and its metabolites.
A quantitative measure of nonlinearity
Authors: Emancipator K , Kroll M H 
Published: January 2020

Abstract
Quantitative measures of the nonlinearity of an analytical method are defined as follows: the "(dimensional) nonlinearity" of a method is the square root of the mean of the square of the deviation of the response curve from a straight line, where the straight line is chosen to minimize the nonlinearity. The "relative nonlinearity" is defined as the dimensional nonlinearity divided by the difference between the maximum and minimum assayed values. These definitions may be used to develop practical criteria for linearity that are still objective. Calculation of the nonlinearity requires a method of curve-fitting. In this article, we use polynomial regression to demonstrate calculations, but the definition of nonlinearity also accommodates alternative nonlinear regression procedures.
Glycated calmodulin from platelets as an index of glycemic control
Authors: Muruganandam A , Romsa G J , Thibert R J , Cheung R M , Draisey T F , Mutus B 
Published: January 2020

Abstract
In an effort to test whether a significant fraction of calmodulin would become glycated within the life span of the platelet (10-14 days), we monitored the kinetics of calmodulin glycation in vitro. Under the conditions we used, the fraction of glycated calmodulin reached a maximum (approximately 21%) within 10 days. We then extended the studies to human subjects. The intraplatelet concentrations of calmodulin and glycated calmodulin from age-matched type I diabetic subjects were monitored by a combination of m-aminophenylboronate affinity chromatography and enzyme-linked immunosorbent assay. The results indicate that the concentrations of total intraplatelet calmodulin (nonglycated plus glycated) were not dependent on the glycemic state of the subjects. Data from control and diabetic subjects showed a poor correlation between the concentrations of glycohemoglobin and of glycated calmodulin. However, a better correlation was obtained when glycated calmodulin concentrations were compared with those of serum fructosamine. The fraction of glycated calmodulin in the control population (7.71% +/- 0.75%) was significantly (P &lt; 0.05) different from that of the diabetic population (21.6% +/- 1.26%). Given that the clinical role of the fructosamine assay remains controversial, estimation of glycated calmodulin in platelets might be useful as a short time-window index of glycemic control.
Reference intervals for 21 clinical chemistry analytes in arterial and venous umbilical cord blood
Authors: Perkins S L , Livesey J F , Belcher J 
Published: January 2020

Abstract
Reference intervals were determined for 21 clinical chemistry analytes in umbilical cord arterial and venous blood from healthy term infants. Nonparametric analysis (rank number) was used to determine the central 95% reference interval. No significant differences were observed between male and female infants. Reference intervals for glucose, urea, creatinine, urate, phosphate, calcium, albumin, total protein, cholesterol, triglycerides, alkaline phosphatase, alanine aminotransferase, aspartate aminotransferase, creatine kinase, lactate dehydrogenase, gamma-glutamyltransferase, and magnesium all were significantly different from adult values.
Comparison of cyclosporin G (Nva2-cyclosporin) concentrations measured in whole blood by monoclonal fluorescence polarization immunoassay, monoclonal radioimmunoassay, and HPLC
Authors: Annesley T M , Coombs R C , Orsulak P J 
Published: January 2020

Abstract
Two commercial monoclonal immunoassays for monitoring cyclosporin A were used to measure whole-blood concentrations of the immunosuppressant cyclosporin G (CsG) in renal transplant patients. We performed a three-way comparison of these two immunoassays and HPLC. Although the two immunoassays agreed favorably, both the monoclonal fluorescence polarization immunoassay and the monoclonal RIA yielded higher CsG results for patients' specimens than did the liquid-chromatographic assay. The experimental data indicate that the observed differences are most likely due to the cross-reactivity of CsG metabolites in the immunoassays.
Inaccuracy of osmometry for measurement of plasma water in acute diabetes mellitus
Authors: Davidson D F 
Published: January 2020

Abstract
Osmometry is reportedly a relatively imprecise technique for the measurement of plasma water. However, reconsideration of the theoretical background of the test reveals that it is also likely to be inaccurate and subject to both positive errors as well as viscosity-dependent negative errors simultaneously, when applied to samples from patients admitted in acute diabetes mellitus. This was confirmed by comparison with Waugh's method of results for 59 specimens from 14 cases. Plasma water was shown to be relatively underestimated at high protein concentrations and overestimated at lower ones.
Simultaneous Determination of Free Testosterone and Testosterone Bound to Non-Sex-Hormone-Binding Globulin by Equilibrium Dialysis
Authors: Barini Angela , Liberale Italiana , Menini Edoardo 
Published: January 2020

Abstract
We describe a procedure based on equilibrium dialysis that allows the simultaneous determination of free testosterone and testorerone bound to non-sex-hormone-binding globulin (non-SHBG) in plasma. After saturating SHBG with 5α-dihydrotestosterone (DHT) according to a technique recently described, the percentage of free testosterone in the treated and the untreated samples is measured by equilibrium dialysis with use of a semiautomated instrument that allows rigorous standardization of the experimental conditions. The present method is simpler and faster than the previously described technique in which, after the saturation of SHBG with DHT, the unbound fractions were measured by centrifugal ultrafiltration dialysis. The method is also reproducible and suited for the analysis of a large number of samples. The technique has been applied to the determination of the fractional distribution of testosterone in plasma pools from normally menstruating, pregnant, and postmenopausal women and from normal men.
Transferrin allelic variants may cause false positives in the detection of cerebrospinal fluid fistulae
Authors: Sloman A J , Kelly R H 
Published: January 2020

Abstract
Variations in either the polypeptide sequence or the carbohydrate moieties of transferrin may result in altered electrophoretic mobility of this molecule. We report a case of an allelic (polypeptide) variant of transferrin with mobility similar to that of the beta 2 (sialic acid-depleted) transferrin found in cerebrospinal fluid (CSF) and a few other body fluids. Allelic variation and other transferrin anomalies may be mistaken for the CSF isoform, resulting in false diagnoses of CSF fistulae.
Profiles of very-long-chain fatty acids in plasma, fibroblasts, and blood cells in Zellweger syndrome, X-linked adrenoleukodystrophy, and rhizomelic chondrodysplasia punctata
Authors: Schutgens R B , Bouman I W , Nijenhuis A A , Wanders R J , Frumau M E 
Published: January 2020

Abstract
Profiles of saturated very-long-chain (&gt; C22) fatty acids were studied in plasma, fibroblasts, erythrocytes, platelets, and leukocytes of patients affected by peroxisomal disorders such as Zellweger syndrome, X-linked adrenoleukodystrophy (X-ALD), and classic rhizomelic chondrodysplasia punctata (RCDP) and in controls. In Zellweger patients, the concentration of hexacosanoic acid (C26:0) and the C26:0/C22:0 ratio are greatly increased in plasma and fibroblasts. However, the plasma concentration of docosanoic acid (C22:0) is greatly decreased. Also in platelets, leukocytes, and to a lesser extent erythrocytes, the C26:0 concentrations and both the C26:0/C22:0 and C24:0/C22:0 ratios are greatly increased. The C24:0/C22:0 ratio is significantly increased in plasma, platelets, and leukocytes, but not in erythrocytes. In X-ALD, the C26:0 concentration and the C26:0/C22:0 and C24:0/C22:0 ratios are significantly increased in plasma, fibroblasts, platelets, and leukocytes, but the erythrocytes show substantial overlap in the 5-90% ranges between controls and patients. In RCDP, slightly increased C26:0 and C26:0/C22:0 ratios are found in erythrocytes, platelets, and leukocytes, but not in plasma and fibroblasts. We conclude that plasma and fibroblasts are the specimens of choice for biochemical diagnosis of Zellweger syndrome and X-ALD, respectively. The slight increase in C26:0 in blood cells of RCDP patients suggests a decreased flux of very-long-chain fatty acids through the peroxisomal beta-oxidation pathway in liver in this genetic disorder.
Evaluation of evacuated blood-collection tubes: effects of three types of polymeric separators on therapeutic drug-monitoring specimens
Authors: Landt M , Smith C H , Hortin G L 
Published: January 2020

Abstract
The potential of three types of separator materials found in conventional blood-collection tubes for interference in therapeutic drug measurements was assessed. None of the separators (based on acrylic, silicone, or polyester polymers) had any significant effect on the concentrations of seven drugs (theophylline, digoxin, phenytoin, phenobarbital, gentamicin, ethanol, and cyclosporine) in blood specimens that were processed and analyzed promptly. Storage of specimens for 24 h resulted in an average 2.4% increase in theophylline values in specimens collected in tubes with the acrylic separator (P = 0.024); an average 8.1% decrease in phenytoin in specimens collected in tubes with the polyester-based separator (P &lt; 0.001); and an average 4.2% decrease in phenobarbital in specimens collected in tubes with the polyester-based separator (P = 0.02). All other drug concentrations were not significantly affected. A small decrease in phenytoin (7.9%; P &lt; 0.01) was seen when the specimen volume in 7-mL tubes containing polyester-based separator was reduced to 1.0 mL; all other drug concentrations were unaffected by partial filling of tubes. Paired blood specimens from pediatric patients, when collected in plain tubes and tubes containing acrylic separator, yielded no significant differences for theophylline, digoxin, tobramycin, phenytoin, or phenobarbital concentrations. The three commercially available separators had only small effects on therapeutic drug concentrations, and a newly developed separator based on an acrylic resin was suitably inert.
Substantial urinary concentrations of material resembling beta-core fragment of chorionic gonadotropin beta-subunit in mid-menstrual cycle
Authors: Neven P , Iles R K , Howes I , Sharma K , Shepherd J H , Edwards R , Collins W P , Chard T 
Published: January 2020

Abstract
We measured the day-to-day variations in concentrations of beta-core, luteinizing hormone (LH), and alpha-subunit in urine during the menstrual cycle. The alpha-subunit concentrations showed a pattern similar to that of the LH concentrations. beta-Core-like material was increased during and up to 3 to 4 days after the surge in urine LH. The urine LH concentration was associated with the presence of beta-core immunoreactivity during the urine LH peak. Chromatography showed that, at the peak LH concentration and at 2 days after the LH peak, beta-core immunoreactivity could be accounted for by the presence of a peptide of low molecular mass similar to the beta-core molecule of hCG, but probably originating from the degradation of LH. The prolonged excretion of gonadotropin metabolites in the midcycle must be considered when beta-core is being assessed as a tumor marker.
Applications of a microfabricated device for evaluating sperm function
Authors: Kricka L J , Nozaki O , Heyner S , Garside W T , Wilding P 
Published: January 2020

Abstract
Mesoscale structures (microns dimensions, nL-pL volumes) have been designed and fabricated in silicon for use in various analytical tasks. We studied sperm motility and performed sperm selection in channels (80 microns wide x 20 microns deep), branching structures (40 microns wide x 20 microns deep, eight bifurcations), and channels containing barriers (7 microns feature size). Sperm-cervical mucus and sperm-hyaluronic acid interactions were assessed by using appropriate microchannel-chamber structures filled with either cervical mucus or hyaluronic acid. Simultaneous assessment of the potency of different spermicides (e.g., nonoxynol-9, C13G) and spermicide concentrations was achieved with structures comprising chambers containing spermicide connected via channels to a central chamber into which semen was introduced. Semen was also tested for the presence of sperm-specific antibodies by using microchannels filled with human anti-IgG antibody-coated microbeads.