bluuebunny/crossref_metadata_2025_split huggingface dataset:
Development and validation of a two-site immunoradiometric assay for human atrial natriuretic factor in unextracted plasma.
Authors: Lewis H M , Ratcliffe W A , Stott R A , Wilkins M R , Baylis P H 
Published: January 2020

Abstract
This two-site immunoradiometric assay (IRMA) for human atrial natriuretic factor (ANF)99-126 in plasma utilizes a mouse monoclonal antibody raised against rat (r) ANF103-125 with specificity directed towards the ring structure of ANF, and a rabbit antiserum to human (h) ANF99-126. The monoclonal antibody is radioiodinated, and the IgG fraction of the antiserum is coated onto wells of a microtiter plate. Plasma or standard hANF99-126 (150 microL) is incubated with the radioligand in coated wells for 24 h. The detection limit is 0.9 pg per well, corresponding to 2 pmol/L, with a working range (CV less than 10%) from 4.5 to 540 pmol/L. Intra- and interassay precision are 7% and 9%, respectively, and the assay is unaffected by plasma matrix. In humans, the IRMA is specific for hANF99-126, the major circulating form of ANF, and does not cross-react with metabolites having deletions at the carboxy terminus. Plasma IRMA values in normal seated subjects were 6.6 +/- 1.5 (SEM) pmol/L and results correlated with those of an extraction RIA (r = 0.81, P less than 0.001).
Glycated hemoglobin in fractionated erythrocytes.
Authors: Nakashima K , Nishizaki O , Andoh Y , Takei H , Itai A , Yoshida Y 
Published: January 2020

Abstract
Erythrocytes were fractionated, by centrifugation, on the basis of cell density, which is proportional to cell age. Glycated hemoglobin (Hb A1c) in the fractionated cells was measured and compared with the Hb A1c in whole blood and with the fructosamine concentrations in plasma of normal and diabetic subjects. In normal subjects, Hb A1c increased according to the age of the erythrocytes, but hyperbolically rather than linearly, indicating the slow conversion of Hb A to Hb A1c with saturability. The greatest correlation of Hb A1c with plasma fructosamine was in younger middle-aged cells. A subgroup of subjects with impaired glucose tolerance had high Hb A1c in older cells. Hb A1c of the young cells reflects recent glycemic status, for monitoring the initial stage of the treatment of diabetics, whereas Hb A1c of the older middle-aged cells more specifically reflects the longer term glycemic status, for screening and for the long-term monitoring index for treatment of diabetes.
Cocaine and pregnancy: clinical and toxicological implications for the neonate.
Authors: Chasnoff I J , Lewis D E , Griffith D R , Willey S 
Published: January 2020

Abstract
Recent studies show that the rate of cocaine use by pregnant women in the United States is much higher than realized hitherto, and an increasing number of infants are being born to cocaine-using mothers. In an ongoing research project to study the effects of cocaine on pregnancy outcome, we studied 70 infants born to cocaine-using women. These infants were matched to a drug-free comparison group selected from the population of the same hospital: children of pregnant women of a similar racial and socioeconomic distribution, but with no history or evidence of licit or illicit drug use during pregnancy. Cocaine-exposed infants had lower birth weight, shorter gestation, and a smaller head circumference than control infants. Cocaine-exposed infants also had neurobehavioral abnormalities at initial evaluation and a higher rate of perinatal complications. Toxicological evaluation of urines of neonates born to cocaine-using women showed that benzoylecgonine, a primary metabolite of cocaine, persisted in the urines for as long as 120 h after delivery. We discuss the role of the immature fetal and neonatal system in the clinical and toxicological outcome of the infant, and emphasize that further long-term studies of this will be needed.
HPLC measurement of chlorophenoxy herbicides, bromoxynil, and ioxynil, in biological specimens to aid diagnosis of acute poisoning.
Authors: Flanagan R J , Ruprah M 
Published: January 2020

Abstract
A simple high-performance liquid-chromatographic assay for eight chlorophenoxy (2,4-D and related compounds) and two benzonitrile (bromoxynil and ioxynil) herbicides has been developed to aid in the diagnosis of acute poisoning. Sample (whole blood, plasma/serum, urine, or tissue homogenate) or standard (100 microL) is vortex-mixed (ca. 5 s) with 20 microL of internal standard solution [1.00 g/L 2,4,5-TP in 0.02 mol/L Tris buffer, pH 9.6:methanol (1 + 1)]. Dilute (0.2 mL/L) hydrochloric acid in methanol, 200 microL, is added and the mixture is again vortex-mixed (30 s). After centrifugation (9950 X g, 2 min) a 10-20 microL portion of the supernate is analyzed on a 250 X 5 mm (i.d.) Spherisorb S5 Phenyl column, with aqueous potassium dihydrogen orthophosphate (50 mmol/L, pH 3.5) and acetonitrile (3 to 1 by vol) at a flow-rate of 1.8 mL/min as eluent. The method is capable of resolving the chlorophenoxy/benzonitrile mixtures (2,4-D/MCPP, 2,4-D/DCPP, 2,4-D/ioxynil, 2,4-D/MCPP/DCPP, 2,4-D/2,4,5-T, and MCPP/ioxynil) encountered in the U.K. The limit of detection (at 240 nm) is 20 mg/L (10 mg/L for bromoxynil and ioxynil). Intra-assay and interassay CVs were less than 5% and less than 8%, respectively, for all analytes. Plasma:whole blood distribution ratios ranged from ca. 1.7 for 2,4-DB to ca. 2.0 for 2,4-D, emphasizing that results of whole-blood measurements must be multiplied by a factor of ca. 2 for comparison with plasma/serum data.
Standardization of apolipoprotein B and A-I measurements.
Authors: Albers J J , Marcovina S M 
Published: January 2020

Abstract
Apolipoprotein B, the major protein of low-density lipoprotein, and apolipoprotein A-I, the major protein of high-density lipoprotein, can serve as important predictors of atherosclerotic cardiovascular disease. However, these apolipoprotein measurements have not realized their full potential because of inadequate standardization. Purified apolipoprotein A-I of known absolute mass, in lyophilized form, can serve as primary standard for apolipoprotein A-I, and freshly isolated low-density lipoprotein of narrow density range can serve as primary standard for apolipoprotein B. These primary standards can be used to assign target values to secondary reference material and calibrators by reference laboratories using standardized, validated immunoassay procedures. Lyophilized serum can serve as secondary reference material for apolipoprotein A-I. Freshly frozen serum pools should be used as reference material for apolipoprotein B until more practicable materials that do not exhibit matrix interactions are developed. Implementation of proper standardization procedures can lead to significant improvements in apolipoprotein measurements.
Lipoprotein(a) quantified by an enzyme-linked immunosorbent assay with monoclonal antibodies.
Authors: Labeur C , Michiels G , Bury J , Usher D C , Rosseneu M 
Published: January 2020

Abstract
This new, sensitive, specific "sandwich"-type enzyme-linked immunosorbent assay (ELISA) for quantifying lipoprotein(a) [Lp(a)] in human serum and in ultracentrifugal lipoprotein fractions is based on use of a monoclonal antibody raised against apolipoprotein(a) as coating protein and a polyclonal antibody, raised against either apo B or against Lp(a) and conjugated with peroxidase, for detection of bound Lp(a). Mean intra- and interassay CVs for assay of 16 samples were 3.0% and 5.6%, respectively. Sample pretreatment with urea did not enhance Lp(a) immunoreactivity, and treatment with nonionic detergents decreased binding to the monoclonal antibody. Results correlated well (r = 0.99, n = 38) with those by radial immunodiffusion (RID). The ELISA assay, however, detects amounts corresponding to Lp(a) contents of 10 to 1000 mg/L in plasma samples diluted 1000-fold, compared with 100-500 mg/L for RID. For 92 normolipidemic subjects, the mean Lp(a) concentration was 120 (SD 130) mg/L. In patients undergoing coronary angiography, Lp(a) concentrations increased with the severity of the disease but were not correlated with either HDL cholesterol, triglycerides, apo A-I, or apo B, and only weakly with plasma cholesterol and apo A-II. These two correlations were even weaker in normal subjects, and only the correlation with total cholesterol was valid. Lp(a), measured at birth and at seven days and six months, steadily increased with age. This assay is well suited for measuring Lp(a) in plasma and in lipoprotein fractions and also for screening programs evaluating this significant genetic risk factor for the development of atherosclerosis.
Improved radioimmunoassay of atrial natriuretic peptide in plasma.
Authors: Poiesi C , Rodella A , Mantero G , Cannella G , Ferrari R , Albertini A 
Published: January 2020

Abstract
We describe a radioimmunoassay (RIA) for measurement of atrial natriuretic peptide (ANP), based on one-step incubation and a simplified extraction procedure. The extraction was performed on a "Supelclean LC 18" column, with 2-mL plasma samples. Use of a diiodinated tracer improved the sensitivity of the RIA method. The minimal detectable value was 5 ng/L. Simplification of the extraction procedure and simultaneous incubation of the reagents provide a method more suitable for routine standard assay of ANP than those currently available. Intra- and interassay CVs were 6% (n = 12) and 11% (n = 10), respectively. The mean concentration of ANP in plasma of 32 healthy volunteers was 33 (SEM 4) ng/L. The ANP values for plasma after one-step incubation correlated well with those determined by a commercial RIA kit: r = 0.971, slope = 1.099, intercept = 1.949 ng/L (n = 25).
Re-evaluation of the diagnostic utility of serum total creatine kinase and creatine kinase-2 in myocardial infarction.
Authors: Leung F Y , Galbraith L V , Jablonsky G , Henderson A R 
Published: January 2020

Abstract
The diagnostic utility of total creatine kinase activity (I), creatine kinase-2 isoenzyme activity (II), and II as a percentage of I, was examined by receiver-operating characteristic curve and likelihood ratio (LR) analyses in 310 persons admitted to the Coronary Care Unit (151 proven cases of myocardial infarction and 159 non-myocardial infarction controls), from whom blood was sampled at 6-h intervals for 48 h after the onset of chest pain. I was ineffective either as a "rule-in" or as a "rule-out" test within the first 6 h of the onset of chest pain; thereafter, it was an effective test. II was the most effective test during the entire 48-h period. III was more effective than I in the first 24-h period, but was less effective than I during the next 24-h period. The decision threshold for high test sensitivities varies with time over the entire 48-h period, but remains constant for high test specificities. It is essential to tabulate the LR(+) and LR(-) values for both test sensitivity and specificity at constant values to determine the utility of each test at each time interval for respectively ruling out or ruling in a diagnosis of myocardial infarction.
Chemiluminescent assay of alkaline phosphatase applied in an ultrasensitive enzyme immunoassay of thyrotropin.
Authors: Bronstein I , Voyta J C , Thorpe G H , Kricka L J , Armstrong G 
Published: January 2020

Abstract
We compared a chemiluminescent assay and a colorimetric endpoint assay for measuring an alkaline phosphatase (EC 3.1.3.1) label in an enzyme immunoassay of thyrotropin (TSH). The substrate in the chemiluminescent assay is a derivative of adamantyl 1,2-dioxetane phosphate. On dephosphorylation, catalyzed by alkaline phosphatase, the 1,2-dioxetane decomposes further and emits a glow of light (lambda max 470 nm). We modified the Hybritech Tandem-E TSH High Sensitivity assay for chemiluminescent detection of bound alkaline phosphatase label by using this substrate (with 20-, 40-, and 60-min incubations). Detection limits (mean +2 SD of zero standard) were 6.0, 5.2, and 4.5 micro-int. units/L for these incubation periods, respectively, vs 20 micro-int. units/L for the conventional colorimetric version of the assay. Comparison of results for 44 clinical specimens assayed by the chemiluminescent (20-min incubation, y) and colorimetric (60-min endpoint, x) TSH immunoassays gave statistical values of: slope = 1.17, intercept = -0.22, and r = 0.98. Hemoglobin, but not bilirubin, lipids, or protein, interfered; but these interferents were removed by the washing steps in the enzyme immunoassay.
Elimination of caffeine interference in HPLC determination of urinary nicotine and cotinine.
Authors: Thuan N T , Migueres M L , Roche D , Roussel G , Mahuzier G , Chretien J , Ekindjian O G 
Published: January 2020

Abstract
We report an analytical reversed-phase liquid-chromatographic procedure for quantifying nicotine and cotinine in urine, taking into account the presence of interfering caffeine frequently encountered in such specimens. These analytes are extracted from the alkalinized urine with chloroform. After evaporation of the chloroform, the residue is dissolved in methanol and injected into a chromatographic C18 column. Extraction recoveries averaged 80% to 97%. Chromatographic conditions were investigated to obviate caffeine interference. The proposed eluent mobile phase is a polar mixture of water, acetonitrile, methanol, and a pH 4 acetoacetate buffer (65/2/29/4 by vol) adjusted to pH 4.30 +/- 0.02 with triethylamine. High resolution and linearity were obtained for each analyte up to a concentration of 200 mg/L. The minimum detectable amount of each compound was 20 ng per injection, corresponding to 10 micrograms per liter of urine. Correlation with results of gas-liquid chromatography was excellent (r = 0.99). This simple, rapid procedure allows routine screening of tobacco exposure with acceptable precision: within- and between-run coefficients of variation were less than 2% and less than 5%, respectively.
Urinary organic acid excretion by babies born before 33 weeks of gestation.
Authors: Walker V , Mills G A 
Published: January 2020

Abstract
Using analytical procedures that are widely used by laboratories investigating metabolic disorders, we investigated urinary organic acid excretion by premature neonates who were receiving the usual clinical care. Our purpose was to provide a basis for the diagnosis of inherited organic acid defects. We analyzed 127 random (untimed) urine samples collected weekly from 22 infants of 25-32 weeks of gestation (median, 28 weeks). A wide variety of organic acids was excreted. After oximation, they were extracted with ethyl acetate and diethyl ether, derivatized to trimethylsilyl forms, and analyzed by gas-liquid chromatography on a nonpolar fused silica capillary column, with mass spectrometry for identification. Profiles for individual babies varied markedly on different occasions, reflecting their metabolic status and bacterial activity in the gut. There was no significant ketonuria. Three metabolites identified for the first time in urine from normal neonates were 2,3-butanediol, 3-hydroxy-2-butanone (acetoin), and 4-hydroxy-3-methoxyphenyllactic acid. Significantly increased excretion of 4-hydroxyphenyllactic acid and other phenolic acids occurred during parenteral feeding.
Dimethylmethylene blue-based spectrophotometry of glycosaminoglycans in untreated urine: a rapid screening procedure for mucopolysaccharidoses.
Authors: de Jong J G , Wevers R A , Laarakkers C , Poorthuis B J 
Published: January 2020

Abstract
Glycosaminoglycans (GAGs) are measured in urine to screen for mucopolysaccharidoses. Other assay procedures are only qualitative (spot tests), can give false-negative results (spot tests, turbidity tests), or are relatively laborious (uronic acid-carbazole test). The present spectrophotometric procedure, based on the color reaction with dimethylmethylene blue (DMB), can be performed directly on untimed urine samples without prior precipitation. Reference values were age dependent. We tested urines of 27 patients with various mucopolysaccharidoses and compared results by three other procedures (cetylpyridinium chloride turbidity tests at pH 4.8 and at pH 7.0, and the uronic acid-carbazole test). In the DMB assay, GAGs were increased in 26 of the 27 patients. The exception was a Morquio A patient, whose activity of the defective enzyme was higher than in classical Morquio patients. Uronic acid, measured in precipitated GAG by the carbazole test, was increased in 23 of the 25 patients so tested. In the turbidity test at pH 7.0, values were increased in 24 of the 27 patients. In contrast, with the citrate-buffered (pH 4.8) turbidity measurement, GAG content was increased in only 19 of the 27 patients. This rapid and easy DMB method is a reliable screening procedure for mucopolysaccharidoses and compares well with procedures used hitherto.
Depressed activities of purine enzymes in lymphocytes of patients infected with human immunodeficiency virus.
Authors: Renouf J A , Wood A , Frazer I H , Thong Y H , Chalmers A H 
Published: January 2020

Abstract
Enzyme activities were studied in peripheral blood lymphocytes from patients infected with, or at risk for, infection with human immunodeficiency virus (HIV). No significant differences were observed in the HIV-infected and HIV-seronegative high-risk patients with regard to enzyme activities of hypoxanthine-guanine phosphoribosyltransferase (EC 2.4.2.8) and purine nucleoside phosphorylase (EC 2.4.2.1) in peripheral blood. Adenosine deaminase (EC 3.5.4.4) was significantly (P less than 0.02) depressed in asymptomatic HIV-seropositive patients and HIV-seronegative patients at high risk of HIV infection as compared with a healthy HIV-seronegative population. Adenosine kinase (AK, EC 2.7.1.20) was significantly increased in the asymptomatic seropositive (P less than 0.02) and also in the HIV-seronegative high-risk groups (P = 0.01) compared with the normal controls. AK activity was significantly lower in subjects with AIDS than in the asymptomatic (P less than 0.002) and high-risk groups (P less than 0.01). Taken together, these results indicate that adenosine deaminase and AK activities are influenced by the health of the patient, and that measurement of AK activity may prove useful in monitoring the clinical progress of patients with HIV infection.
Fluorometric determination of magnesium in serum with 2-hydroxy-1-naphthaldehyde salicyloylhydrazone.
Authors: Ioannou P C , Konstantianos D G 
Published: January 2020

Abstract
This simple, rapid, sensitive fluorometric method for determining magnesium is based on formation of a fluorescent complex of magnesium with 2-hydroxy-1-naphthaldehyde salicyloyl-hydrazone in alkaline ethanolic medium (lambda ex = 420 nm, lambda em = 460 nm). The detection limit of the method is 0.05 microgram/L (2 nmol/L) and the relative standard deviations (CVs) are 0.8%, 1.1%, and 2.5% at magnesium concentrations of 50, 5.0, and 0.50 microgram/L, respectively. The standard curve is linear from 0 to 250 micrograms/L (0-10 mumol/L). We investigated the chemistry of the reaction, and have applied the method to determine magnesium in 100-fold-diluted, otherwise untreated serum samples. Within-run CVs for the method were 1.7%, 1.1%, and 1.3% at mean magnesium concentrations of 15.7, 26.4, and 36.2 mg/L, respectively. Day-to-day CVs were 2.7%, and 3.6% at mean magnesium concentrations of 10.1 and 25.5 mg/L, respectively. Samples from 96 hospitalized patients in intensive-care units were analyzed by the proposed method (y) and by an automated colorimetric method involving Magon sulfonate reagent (x). Linear regression analysis of the results yielded: y = 1.01x - 0.04 (r = 0.982, Sxy = 0.90).
Evaluation of the biotinylated (Blugene) vs 32P-labeled cDNA probes of beta-glucocerebrosidase: relative sensitivities in genomic and other systems.
Authors: Strasberg P 
Published: January 2020

Abstract
The sensitivity, rapidity, and ease of use of biotinylated (Blugene, Bethesda Research Laboratories) and 32P cDNA probes have been compared, the probe being the cDNA for beta-glucocerebrosidase (EC 3.1.2.45). With the Blugene kit I could detect 2 pg of biotinylated DNA on dot blots. However, under conditions of hybridization, the lower limit of detection for unlabeled cDNA (transblotted onto nitrocellulose) by its labeled counterpart was 5000-fold smaller (10 pg vs 50 ng) for the isotopically labeled probe. 32P- and Blugene-probes hybridized detectably with 0.5 and 10 micrograms, respectively, of transblotted EcoR 1-digested genomic DNA, making the radioactive method 20 times as sensitive. However, color development was complete within 30 min to 3 h, whereas radioautoradiography required 12 h to one week. Blugene was also safer, easy to use, and effective under appropriate conditions. The 32P method is expensive, hazardous, time-consuming, and technically difficult. This nonisotopic procedure represents a desirable improvement in biotechnology.
Tumor-derived activated cells: preliminary laboratory and clinical results.
Authors: Oldham R K , Maleckar J R , Friddell C S , Lewko W M , West W H , Yannelli J R 
Published: January 2020

Abstract
It is well known that T lymphocytes can mediate significant anti-tumor responses. A limiting factor has always been the ability to expand T cells, whether from the peripheral blood, spleen, or tumor. The recent availability of recombinant interleukin-2 (r-IL2) has demonstrated the feasibility of expanding T cells and the clinical efficacy of these cells as anti-tumor effectors in murine models. Concomitantly, researchers discovered that lymphokine-activated killer cells--peripheral blood cells functionally distinct from T cells--could be cultured, expanded, and re-infused in patients, with significant clinical effects. For many years, the infiltrating lymphocytes have been recognized in tumor biopsies and known to be cytolytically active. Major limiting factors were the ability to culture large numbers of these infiltrating cells and the limited understanding of the tumor antigens involved for T-cell stimulation. Restimulation by antigen (tumor cells) appears to provide the ongoing antigen stimulation needed to maintain selective killing of tumor cells. By defining various factors in the medium that support and enhance T-cell growth and activation, the components are becoming available to develop a broad attack on advanced cancer by using this laboratory-based technology of stimulation and expansion of tumor-derived activated cells.
Radioimmunoassay of testosterone not bound to sex-steroid-binding protein in plasma.
Authors: Déchaud H , Lejeune H , Garoscio-Cholet M , Mallein R , Pugeat M 
Published: January 2020

Abstract
To measure the concentration of testosterone (T) that is not bound to sex-steroid-binding protein (SBP) in plasma, we quantified by radioimmunoassay the T in the supernates of plasma samples after precipitation with 50%-saturated ammonium sulfate. The concentrations of non-SBP-bound T. directly measured with this assay, correlated significantly (P less than 0.001) with those deduced from measurement of the percentage of non-SBP-bound T determined with [3H]T as tracer or from mathematical models according to the law of mass action. It also correlated significantly with the ratio of T to SBP and with the concentration of nonbound T. As determined with this assay, the mean concentration of non-SBP-bound T in normal men was higher in young (4.67, SD 2.68 nmol/L; n = 30) than in older (greater than 40 years) subjects (2.48, SD 1.61 nmol/L; n = 35; P less than 0.001) and lower than normal in hyperthyroid (1.61, SD 0.91 nmol/L; P less than 0.01) or infertile men (3.28, SD 1.70 nmol/L; P less than 0.01). In women, non-SBP-bound T was higher in hirsute patients (0.24, SD 0.11 nmol/L; P less than 0.01) and was lower during pregnancy (0.09, SD 0.05 nmol/L; P less than 0.05) than in normal women during the follicular phase (0.16, SD 0.07 nmol/L). We conclude that this direct measurement of non-SBP-bound T in plasma is suitable for routine use and represents a reliable index of androgenicity in human pathology, particularly when alterations of the binding capacity of SBP modify the concentrations of total T.