bluuebunny/crossref_metadata_2025_split huggingface dataset:
Screening for microalbuminuria in patients with diabetes mellitus: frozen storage of urine samples decreases their albumin content.
Authors: Elving L D , Bakkeren J A , Jansen M J , de Kat Angelino C M , de Nobel E , van Munster P J 
Published: January 2020

Abstract
The influence of storage on urinary albumin concentration was prospectively studied with use of overnight urine specimens (Albustix negative) from 73 diabetic patients. From each urine sample four aliquots were taken. One was stored at 4 degrees C and assayed within two weeks, the other three were stored at -20 degrees C and assayed within two weeks and after two and six months. Albumin concentration was measured with laser immunonephelometry. The detection limit, 1 mg/L, suffices for the screening of diabetic patients for microalbuminuria. After storage for two and six months at -20 degrees C, significantly lower albumin concentrations were found. The difference was mainly caused by lower concentrations found in urine samples in which a precipitate had formed, which was the case in 22 and 25 samples, respectively. Thus, freezing of urine samples for determination of low concentrations of albumin may yield falsely low results. Urine samples are best stored at 4 degrees C and assayed within two weeks.
Proficiency testing in a medical-needs context.
Authors: Lott J A , Manning N R , Kyler M K 
Published: January 2020

Abstract
Proficiency testing by State and Federal agencies is an ongoing activity of clinical laboratories and an occasional source of anxiety; strict statistical evaluations of "snapshot" laboratory values are inappropriate and medical-needs criteria should be used. The quality of laboratory results largely depends on available technology. Fortunately, for most of the common clinical chemistry analytes there has been a steady reduction of imprecision during the past 20 years. Proficiency testing may have been the stimulus for this improved performance. Medical-needs criteria differ, depending on the testing goal. For proficiency testing, population screening criteria are appropriate, e.g., the College of American Pathologists fixed criteria for the common tests. Stricter criteria are needed for short-term (inpatient) and long-term (outpatient) monitoring of laboratory data. Explicit proficiency-testing limits are given here for nine of the common clinical chemistry tests for each of the three medical-needs criteria described above. The limits consider total error--i.e., bias from the believed correct value, and imprecision. Rather broad limits are acceptable for the commonly performed enzyme tests when used for screening purposes.
Rapid, reliable in vivo assays of human phosphate metabolites by nuclear magnetic resonance.
Authors: Bottomley P A , Hardy C J 
Published: January 2020

Abstract
This accurate, reliable, and fast method of assaying absolute concentrations of phosphate metabolites noninvasively in living tissue, including that of humans, combines 31P nuclear magnetic resonance (NMR) spectroscopy and 1H NMR imaging. The images are used to measure the areas of metabolite-bearing tissue in selected sections through the subject, and 31P spectra are acquired from the same section, together with a concentration reference located on the periphery. Metabolite concentrations are calculated from the ratios of areas and integrated signal intensities. Apparatus and protocol are designed to eliminate corrections due to magnetic field nonuniformities and NMR relaxation times. Mean (and SD) concentrations of adenosine triphosphate (ATP), phosphocreatine, and inorganic phosphate (Pi) measured in the brains of 15 normal adult human volunteers with a 1.5-T NMR system were 3.03 (0.49), 5.18 (0.89), and 1.5 (0.7) mmol per liter of wet tissue, respectively. Acquisition times of only a few minutes should facilitate metabolic studies of patients with disorders in limbs and brain, particularly those affecting entire organs.
Binding of labeled thyroxin analog to serum proteins evaluated after radioimmunoassay of free thyroxin.
Authors: Arevalo G 
Published: January 2020

Abstract
In ambulatory patients, assay of free thyroxin (FT4) in serum correlates well with thyroid status and with results obtained by equilibrium dialysis. The validity of FT4 results has been questioned mainly in euthyroid patients with altered concentrations of thyroid hormone-binding proteins, as in nonthyroidal illness, hereditary analbuminemia, familial dysalbuminemic hyperthyroxinemia (FDH), and the presence of iodothyronine-binding antibodies. I present here a study of the binding of [125I]T4-derivative to serum proteins in the supernate, which is ordinarily discarded after determination of FT4 by one-step radioimmunoassay with dextran-coated charcoal used to separate the free and bound fractions. The results are expressed as a ratio, with results for a normal serum pool as reference. The average ratio was high in hyperthyroid subjects, 1.26 (SD 0.12, n = 25), and in hypoalbuminemia, 1.20 (SD 0.10, n = 15), and low in FDH, 0.62 (SD 0.11, n = 9), and hypothyroid subjects, 0.90 (SD 0.06, n = 20). In normal individuals it was 0.98 (SD 0.05, n = 30). Determination of the analog-binding rate complements the FT4 result and allows for the recognition of cases with abnormal binding by serum proteins, without recourse to other tests recommended for thyroid-function studies.
Emetine identified in urine by HPLC, with fluorescence and ultraviolet/diode array detection, in a patient with cardiomyopathy.
Authors: Lachman M F , Romeo R , McComb R B 
Published: January 2020

Abstract
A 15-year-old girl with a four-month history of cardiac failure from undetermined cause was admitted to the hospital with weakness, fatigue, and weight loss. During her hospitalization she was found to have abused diet aids, laxatives, and cathartics. Although an electrocardiogram revealed nonspecific T-wave abnormalities and laboratory studies showed supranormal enzyme test results for creatine kinase and lactate dehydrogenase, no definite explanation of the cardiomyopathy was forthcoming. Ipecac abuse leading to cardiomyopathy was suspected early in the hospitalization. HPLC analysis of a urine sample showed emetine, a principle component of ipecac, the presence of which was later confirmed by more-specific HPLC analysis with photodiode array detection.
Estradiol-17 beta determined in plasma by gas chromatography-mass spectrometry with selected ion monitoring of mixed silyl ether-perfluoroacyl ester derivatives and use of various stable-isotope-labeled internal standards.
Authors: Dehennin L 
Published: January 2020

Abstract
A highly specific method is described for measuring estradiol-17 beta (E2) in plasma by gas chromatography-mass spectrometry (GC-MS) associated with stable isotope dilution. A mixed derivative, E2-3-trimethylsilyl ether-17-heptafluorobutyrate (E2-3-TMS-17-HFB), was found to have excellent analytical properties. The specificity of the derivatization procedure exploits a unique feature of estrogens: the selective exchange of a phenolic perfluoroacyl ester for a trialkylsilyl ether. No significant differences in E2 concentration could be ascribed to the use of 2H- or 13C-labeled analogs, thus ruling out interferences from possible isotope exchange commonly attributed to deuterated compounds. Precision is closely similar to that for methods in which the more common E2-3, 17-bis(trimethylsilyl) ether and E2-3, 17-bis(heptafluorobutyrate) derivatives are used. Sensitivity and specificity of the mixed 3-TMS-17-HFB derivative allow adequate determinations of E2, even in plasma from males, in 2-mL samples. Interlaboratory mean concentrations of E2 obtained by routine immunoassays were consistently higher than the target values estimated by GC-MS, particularly at concentrations less than 100 pmol/L.
Dependence of the thyroxin/thyroxin-binding globulin (TBG) ratio and the free thyroxin index on TBG concentrations.
Authors: Nelson J C , Tomei R T 
Published: January 2020

Abstract
We studied the dependence of the free thyroxin (T4) index and the ratio of T4 to thyroxin-binding globulin (TBG) on TBG concentrations, using sera from cases of congenital TBG deficiency and congenital TBG excess. Two such sera with similar concentrations of albumin, transthyretin, and free T4 were mixed to provide test samples with TBG concentrations covering the range of clinical interest without changes in the other T4-binding proteins. Total T4, free T4, TBG, triiodothyronine (T3) uptake, and the free fraction of T3 in serum were measured, and we calculated the free T4 indices, T4/TBG ratios, and the free fraction of T4. A 100-fold variation in TBG concentration was associated with a 10-fold variation in total T4, a fourfold variation in T3 uptake, and a 10-fold variation in the T4/TBG ratio. As TBG concentrations increased, the T4/TBG ratio decreased and the free T4 index increased. The free T4 index did not parallel the T4/TBG ratio, and neither the T4/TBG ratio nor the free T4 index reflected the concentrations of free T4 in serum.
Solid-phase enzymoimmunoassay of estrone in saliva.
Authors: Folan J , Gosling J P , Finn M F , Fottrell P F 
Published: January 2020

Abstract
In this solid-phase enzymoimmunoassay for estrone in saliva, microtiter plates are used after extraction of the sample with diethyl ether. No chromatographic step is involved. The detection limit of the assay is 450 fg per well (33 pmol/L). Intra- and interassay coefficients of variation for the assay of low, medium, and high concentrations of estrone in saliva were respectively 4.2, 12.7; 5.2, 8.7; and 2.7, 5.8%. Using this assay, we found a highly significant correlation (P less than 0.001) between estrone concentrations in time-matched serum and saliva samples. The analytical procedure is rapid and relatively simple. One person can assay 50-60 saliva samples during a normal working day. We conclude that the assay is very suitable, even in small laboratories, for saliva estrone measurements, which, in facilitating serial sampling, enables dynamic observations of estrone concentrations and ovarian activity to be more easily made.
High-yield purification of the complex-forming glycoprotein in urine from normal and abnormal subjects.
Authors: Wakui H , Kobayashi R , Itoh H , Imai H , Nakamoto Y , Miura A B 
Published: January 2020

Abstract
Ordinary methods for purification of complex-forming glycoprotein (protein HC) or alpha 1-microglobulin, a protein closely related to protein HC, require either large volumes of urine or special collection of urine specimens from patients with tubular proteinuria. Here we describe a fast, efficient procedure for isolating protein HC in high yield from urines from healthy and diseased subjects, with use of Cibacron blue, hydroxylapatite, and gel chromatography. Using this procedure, we also obtained a considerable amount of polymeric protein HC from the urine of a patient with chronic renal failure. The pattern of charge heterogeneity and immunoreactivity with anti-protein HC differed between the polymeric and monomeric forms of protein HC. We also observed a variability in charge heterogeneity of protein HC among patients with renal disorders. These results demonstrate that this purification method is useful for further studies to elucidate the biochemical properties of protein HC and its clinical significance in renal disorders.
Liquid-chromatographic assay for free and transthyretin-bound retinol-binding protein in serum from normal humans.
Authors: Burri B J , Kutnink M A 
Published: January 2020

Abstract
We quantified vitamin A-transporting retinol-binding protein (RBP) in serum or plasma by size-exclusion "high-performance" liquid chromatography, using a TSK 2000 column and fluorescent detection of the bound retinol. Serum or plasma samples filtered through a 0.20-microns (pore size) Millex filter were applied directly to the column. The pH 7.0 mobile phase contained sodium phosphate, disodium EDTA, and mercaptoethanol. Two peaks with RBP immunological activity were eluted: the smaller peak containing at least 86% of the vitamin A, which was identified as transthyretin-bound RBP; the larger peak containing a small amount (less than 14%) of a highly fluorescent vitamin A-containing protein, identified as free RBP. Both free and transthyretin-bound RBP can be quantified by this method.
Pyroglutamic acidemia in an adult patient.
Authors: Creer M H , Lau B W , Jones J D , Chan K M 
Published: January 2020

Abstract
Pyroglutamic acidemia, a rare metabolic disorder, usually appears in infancy. It is characterized by retardation, ataxia, hemolytic anemia, and chronic acidosis and is caused by a marked deficiency of glutathione synthetase (EC 6.3.2.3) activity. This disease is inherited as an autosomal recessive trait, but the clinical condition is also detected in heterozygotes. We report an unusual case of high-anion-gap metabolic acidosis in a 52-year-old woman who was admitted with neurological complaints and breathing problems but without the characteristic clinical features of congenital glutathione synthetase deficiency. The etiology of the acidosis could not be attributed to ketoacidosis, lactic acidosis, or ingestion of methanol, salicylate, or ethylene glycol. Analysis of the patient's plasma and urine for organic acids revealed the presence of high concentrations of pyroglutamate (5-oxoproline), which remained high throughout her hospitalization.
Standardization of methods for measuring plasminogen activator inhibitor activity in human plasma.
Authors: Chandler W L , Loo S C , Nguyen S V , Schmer G , Stratton J R 
Published: January 2020

Abstract
We have standardized the measurement of plasminogen activator inhibitor type 1 (PAI-1) activity in plasma. One-chain tissue-type plasminogen activator (t-PA; EC 3.4.21.31; final activity, 5 int. units/mL) was incubated with plasma (final dilutions 1:4 to 1:40) in phosphate buffer (pH 7.4, ionic strength = 0.15) for 15 min at 37 degrees C, followed by acidification and measurement of residual t-PA activity by an amidolytic method. The PAI-1 activity assay was 98% specific for PAI-1 activity in samples from both pregnancy and nonpregnancy, and varied linearly with added plasma volume when the percent inhibition of t-PA was between 8% and 50%. For the standardized method, analytical recovery was 93 +/- 5%, the detection limit was 1.6 arbitrary units per milliliter (1 arb. unit of PAI-1 activity = inhibition of 1 int. unit of t-PA activity), and total imprecision was 10.2 (SD 0.7) arb. units/mL (CV = 7%, n = 20). The average PAI-1 activity in 10 healthy individuals drawn between 0800 and 1000 hours was 23.9 +/- 15.4 arb. units/mL. Compared with the standardized assay, two of three previously described assays underestimated PAI-1 activity in plasma by 77% and 85%, respectively.
Enzymatic determination of potassium in serum.
Authors: Berry M N , Mazzachi R D , Pejakovic M , Peake M J 
Published: January 2020

Abstract
This is a kinetic assay for measuring K+ in serum, based on the activation of pyruvate kinase (EC 2.7.1.40) by K+. We eliminated interference from Na+ and NH4+ ions, which also activate this enzyme, by including Na+-binding and NH4+-consuming reagents in the reaction mixture. The assay was developed with and evaluated in the Cobas Fara centrifugal analyzer (and has been used in other kinetic analyzers). Within-run and between-run CVs were less than 1.4% and less than 1.6%, respectively. The reaction rate per millimole of K+ per liter (0.05 delta A/min) was more than double that of the reagent blank (0.02 delta A/min). Results correlated well with those by flame photometry, and interference from bilirubin, hemoglobin, lipids, heparin, and other cations was negligible. This method, in conjunction with a previous method we have reported in which beta-galactosidase is used for measuring Na+ in serum, offers a practical alternative to the use of ion-selective electrodes and flame photometry for measuring these clinically important monovalent cations in high-throughput or "stat" biochemical analyzers.
A simplified and rapid test for acetylator phenotyping by use of the peak height ratio of two urinary caffeine metabolites.
Authors: el-Yazigi A , Chaleby K , Martin C R 
Published: January 2020

Abstract
We describe a simplified liquid-chromatographic test in which acetylator phenotype is determined by measuring the peak height ratio of two urinary caffeine metabolites, 5-acetylamino-6-formylamino-3-methyluracil and 1-methylxanthine. We applied this test to determine the acetylator phenotypes of 52 subjects who regularly drink coffee, tea, or caffeinated beverages. Also, we determined the acetylator phenotypes of these subjects according to a well-established sulfasalazine test, which yielded identical results. We established the reproducibility of the described test by determining the acetylator phenotypes of 10 additional subjects on two different days separated by a period of two to five weeks. Of the 52 subjects examined by both tests, 40 (76.9%) were classified as slow acetylators, which agrees well with the percentage reported elsewhere for 297 similar subjects from the Saudi population.
Concurrent measurement of flecainide acetate and propranolol by normal-phase high-performance liquid chromatography.
Authors: Rognerud C L , Ou C N 
Published: January 2020

Abstract
This simple, isocratic, normal-phase liquid-chromatographic method concurrently measures flecainide acetate and propranolol in 100 microL of serum within 8 min. The chromatographic system consists of a Waters "Resolve" column packed with 5-microns silica spheres and a mobile phase of ammonium sulfate (10 mmol/L, pH 6.8)/methanol (22/78 by vol), pumped at 0.9 mL/min and monitored by a fluorometer (excitation at 225 nm and emission at 340 nm). After 100 microL of serum is mixed with 200 microL of the internal standard solution [N-(2-piperidylmethyl)-2,3-bis(2,2,2-trifluoroethoxy)-benzamide HCl, 2500 micrograms/L] and 200 microL of 0.2 mol/L sodium carbonate, the sample is extracted into butanol/hexane (20/80 by vol). The organic layer is separated and evaporated, and the residue is redissolved in 200 microL of methanol; 50 microL of this is injected onto the column. Relative recovery was 100% over the assay range of 25-2000 micrograms/L for flecainide and 10-2000 micrograms/L for propranolol. Within-run CVs were less than 2% for flecainide and less than 5% for propranolol; day-to-day CVs ranged from 5.0% to 6.5% for flecainide and from 3% to 12% for propranolol.
Lactate dehydrogenase isoenzyme patterns in serum of patients with metastatic liver disease.
Authors: Rotenberg Z , Weinberger I , Davidson E , Fuchs J , Harell D , Agmon J 
Published: January 2020

Abstract
Total lactate dehydrogenase (LD, EC 1.1.1.27) and LD isoenzymes were determined in serum of 170 patients with metastatic liver disease, 35 of whom had multiple metastatic sites. Overall, values of LD were above normal for 78% of the 170 patients. Half of the patients had an isomorphic pattern of LD isoenzymes (i.e., relative increase in all five isoenzymes); the other half had an increased LD-4,5 pattern, mostly a solitary increase in LD-5 only. Of those patients with normal LD values, 92% had the increased LD-4,5 pattern, whereas 70% of patients with LD values greater than 350 U/L had an isomorphic pattern of LD isoenzymes. All 35 patients with multiple metastatic sites had LD activity greater than 350 U/L; in the majority of them (74%) it was greater than 500 U/L; in 31 (89%), the increase was isomorphic. The diagnostic efficiency of the combined LD greater than 225 U/L (upper limit of normal) and increased LD-4,5 test results was much better than that of LD greater than 225 U/L alone (93% vs 74%). We conclude that serum LD and LD isoenzymes should be determined in every patient with suspected liver metastatic disease. The isomorphic pattern of LD isoenzymes is apparently associated with higher values for total LD and was common among the patients with multiple metastatic sites.
Status of drugs-of-abuse testing in urine under blind conditions: an AACC study.
Authors: Frings C S , Battaglia D J , White R M 
Published: January 2020

Abstract
We report results of a blind study designed to determine the accuracy of drugs-of-abuse testing in urine as done in 31 laboratories across the United States. The drugs studied were amphetamines, cannabinoids, cocaine, opiates, and phencyclidine. These laboratories confirmed all positive drug results with a different analytical method. Ten urine samples were sent to each laboratory, which resulted in 1486 trials. There were no false-positive results. The overall accuracy rate was 97%. Our study demonstrates that urine drug testing can be accurate when performed by qualified staff, using up-to-date screening and confirmation methods, appropriate quality-assurance measures, and a chain of custody.
Bedside diagnosis of alcohol intoxication with a pocket-size breath-alcohol device: sampling from unconscious subjects and specificity for ethanol.
Authors: Falkensson M , Jones W , Sörbo B 
Published: January 2020

Abstract
We describe a novel mouth-cup device for sampling breath from unconscious subjects and analysis with a hand-held breath-alcohol instrument, the "Alcolmeter SD-2." This equipment was evaluated in healthy volunteers after they drank a moderate dose of alcohol. Three kinds of breath were analyzed: (a) end-expired air from a conventional mouth-tube, (b) breath sampled from the mouth-cup, and (c) air from a nasal tube supplied with the breath analyzer. The ethanol concentration in breath from the mouth-cup was slightly less than in end-expired air but significantly greater than in nasal air. Results with mouth-tube and mouth-cup correlated highly with blood-ethanol concentration as determined by gas chromatography; nasal-tube air correlated less well. The Alcolmeter responded not only to ethanol but also to methanol, 1-propanol, and 2-propanol, whereas ethylene glycol gave no response. The time-response curve for methanol was different, and this might permit differential diagnosis of methanol poisoning.
Development of a confirmatory enzyme-linked immunosorbent assay for HIV-1 antibodies.
Authors: Chiang C S , Grove T , Cooper M , Cuan J , Kowalski A , Parcells K , Tsunokawa M , Rosenberg M , Arcuri E , Franklin S 
Published: January 2020

Abstract
We subcloned six discrete protein-coding regions representing the gag (Kp24 and Kp55), env (Kp41, Kp120N, and Kp120CC), and pol (Kp66/31) gene products of the human immunodeficiency virus type 1 (HIV-1) and expressed them in Escherichia coli as fusion proteins with the first 56 residues of galactokinase. An enzyme-linked immunosorbent assay for confirming the presence of HIV-1 antibodies was developed by coating the six purified antigens on individual wells of a microtiter plate (the HIVAGEN assay). This assay yielded no false-negative results and fewer indeterminate results than the Western blot assay for 143 specimens from patients with acquired immunodeficiency syndrome (AIDS) or AIDS-related complex (ARC). Analysis of 1016 specimens from seronegative donors by the HIVAGEN assay yielded no false-positive results, and the rate of indeterminate results was substantially lower than for the Western blot assay. The HIVAGEN assay is well suited for routine confirmation of the presence of HIV-1 antibodies because it is objective, quantitative, rapid, precise, and readily automatable.