bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cross-reactivity of monomeric and dimeric biosynthetic human growth hormone in commercial immunoassays
Authors: Bowsher R R , Apathy J M , Ferguson A L , Riggin R M , Henry D P 
Published: January 2020

Abstract
Commercial kits give different measurements for concentrations of growth hormone (GH, somatotropin) in serum. Most notably, a two-site monoclonal-antibody-based immunoradiometric assay (IRMA) from Hybritech routinely yields lower values than do conventional RIAs in which polyclonal antibodies are used. We used purified dimeric biosynthetic human GH as a model compound to investigate the specificity of five commercial immunoassays for size variants of GH. In all five assays, biosynthetic monomeric GH was significantly more potent than pituitary-derived standard GH supplied with the kits. Dimeric GH was significantly less potent than monomer in four of the five assays, and cross-reactivities varied more than fivefold, from 15% to 84%. Using three commercial kits selected for their specificity for dimeric GH, we measured GH in serum samples from 18 normal adults. The mean GH concentrations in serum--0.7 (Hybritech, IRMA), 1.8 (Diagnostic Products, RIA), and 3.1 (Cambridge, RIA) micrograms/L--differed significantly, but in the same rank order as that obtained in the experiments on dimer cross-reactivity.
Massive theophylline overdose with atypical metabolic abnormalities
Authors: Eshleman S H , Shaw L M 
Published: January 2020

Abstract
We report a case of fatal theophylline overdose in a 16-year-old asthmatic boy who presented with seizures, respiratory arrest, and a theophylline concentration of 117 mg/L in serum. His hospital course was complicated by refractory hypotension and severe ischemic necrosis of skeletal muscle, bowel, and liver. The metabolic abnormalities observed early in his hospital course included severe hyperkalemia, hyperphosphatemia, hypermagnesemia, hypocalcemia, and profound metabolic acidosis. These metabolic abnormalities differ from those previously reported in cases of massive theophylline overdose. The metabolic abnormalities observed in this patient probably reflected his extensive ischemic tissue damage with release of intracellular ions and associated acidemia. Markedly increased catalytic activities of creatine kinase, aspartate aminotransferase, and alanine aminotransferase in serum were also noted.
Measurement of glutathione S-transferase pi isoenzyme in plasma, a possible marker for adenocarcinoma of the lung
Authors: Howie A F , Douglas J G , Fergusson R J , Beckett G J 
Published: January 2020

Abstract
Using a specific radioimmunoassay, we measured glutathione S-transferase (GST; EC 2.5.1.18) pi isoenzyme in the plasma of 29 patients diagnosed as having carcinoma of the bronchus. Concentrations of the enzyme were significantly higher (P less than 0.01) than those measured in a control group of 16 patients with respiratory disorders other than malignancy. Although, overall, only 19 (66%) of patients with cancer of the bronchus had increased concentrations of GST pi in plasma, eight of the nine (89%) patients diagnosed as having adenocarcinoma had above-normal concentrations of GST pi. To obviate spuriously high results for GST pi concentrations caused by platelet release, we assayed blood samples collected in "Thrombotect" tubes, which contain inhibitors of platelet activation.
Light-chain ratios of immunoglobulins G, A, and M determined by enzyme immunoassay
Authors: Chui S H , Lam C W , Lai K N 
Published: January 2020

Abstract
We describe an enzyme-linked immunosorbent assay for determination of light-chain ratios for IgG, IgA, and IgM in serum. A commercial serum with known overall kappa and lambda concentrations was used as standard. To capture the respective immunoglobulins, we used antibodies to gamma, lambda and mu chains coated onto microtiter plates. Peroxidase-conjugated anti-kappa and anti-lambda chain antisera were reacted with light chains on the captured immunoglobulins, and the amount of enzyme bound was monitored with o-phenylenediamine and urea-hydrogen peroxide as substrates. Calculation of absorbance ratios allowed determination of kappa and lambda chain concentrations of individual immunoglobulins in the standard and samples. Within-run and between-run CVs (n = 25) ranged from 5.9% to 13.0% for "high," "normal," and "low" kappa/lambda ratios for IgG, IgA, and IgM. The thoroughness of light-chain detection, expressed as, e.g., (IgA kappa + IgA lambda)/(total IgA), for 150 sera was 91-110%. The detection limit was 1 microgram/L. Reference intervals (mean +/- SD) for kappa/lambda ratios in sera from 100 apparently healthy adults were 2.34 +/- 0.80 for IgG, 1.59 +/- 0.40 for IgA, and 1.86 +/- 0.76 for IgM.
Electron-capture gas chromatography as a sensitive method for measuring subnanogram amounts of cholesterol in saliva and urine
Authors: Schwertner H A , Johnson E R , Lane T E 
Published: January 2020

Abstract
This is a sensitive method, suitable for measuring subanogram amounts of cholesterol. Cholesterol and the internal standard, epicoprostanol (5-beta-cholestan-3-alpha-ol), are derivatized with pentafluorobenzoyl chloride and detected by electron-capture gas chromatography. The pentafluorobenzoyl esters of cholesterol and the internal standard are easily formed and possess excellent chromatographic and electron-capturing properties. The lower limit of detection of the method, approximately 100 pg injected, is about 500-fold as sensitive as chromatographic methods involving flame-ionization detection. Within-day and between-day coefficients of variation were 4.2% and 8.2%, respectively, for determinations of a urinary cholesterol concentration of 570 micrograms/L (1.47 mumol/L). Such sensitivity permits analysis for cholesterol in (e.g.) physiological fluids, tissue samples, and cell cultures that contain very low concentrations of cholesterol.
Liquid-chromatographic determination of amiodarone and N-desethylamiodarone in serum
Authors: Ou C N , Rognerud C L , Duong L T , Frawley V L 
Published: January 2020

Abstract
We have developed a stable and simple normal-phase liquid-chromatographic method for simultaneously measuring amiodarone and its metabolite, N-desethylamiodarone, within 8 min. The chromatographic system consists of a 15 cm x 3.9 mm Waters "Resolve" silica column and a mobile phase of ammonium sulfate (17 mmol/L, pH 6.8) and methanol (8/92 by vol), pumped at 1.8 mL/min and monitored at 254 nm. After 250 microL of serum is mixed with 100 microL of 0.36 mol/L NaH2PO4, 100 microL of the internal standard solution (L8040, 6 mg/L), and 200 microL of isopropyl ether, the mixture is vortex-mixed and centrifuged. Fifty microliters of the organic layer is injected onto the column. Relative recovery was 100% over the assay range of 0.1 to 20.0 mg/L for both compounds. Within-run and total (day-to-day) CVs were 3% and 7% for amiodarone and 5% and 8% for N-desethylamiodarone, respectively.
Optimal sites and depths for skin puncture of infants and children as assessed from anatomical measurements
Authors: Reiner C B , Meites S , Hayes J R 
Published: January 2020

Abstract
Postmortem measurements were made of distances from skin surface to underlying bone/cartilage on 43 children (up to 8 y old; weights from 0.7 to 26.4 kg) to determine optimal sites and lengths of lancet tips for skin puncture of the heel, great toe, and middle finger. For measuring depths, a needle-like probe was devised that minimized disfigurement. As long as the infant's heel was available for puncture prior to callus formation (to about six months), it offered the greatest depth and the bone/cartilage of the lateral/medial sites was considerably deeper than posterior sites. At age six months, the mean distance of skin surface. At age six months, the mean distance of skin surface to bone/cartilage in the middle finger was 2.5 mm, the lower 95% prediction interval being 1.5 mm. Lengths of lancet tips for finger puncture should therefore be made less than 1.5 mm. To get the desired volumes of blood, a compromise must be reached between depth and width of the lancet tip.
Biological factors affecting concentrations of serum LpAI lipoprotein particles in serum, and determination of reference limits
Authors: Steinmetz J , Choukaife A , Visvikis S , Henny J , Siest G 
Published: January 2020

Abstract
We used an electroimmunoassay to measure LpAI lipoprotein particles (lipoproteins containing apolipoprotein AI but not apolipoprotein AII) in serum of a presumably healthy population of about 1000 subjects, noting sex- and age-related variations for the age interval four to 70 years. Results were higher for women than men. For males, the value for the 50th percentile of the distribution was highest in the 10- to 14-year subgroup, 0.69 g/L, decreasing to 0.60 g/L in adults. For females, the values increased regularly, from 0.59 g/L at ages four to 10 years to 0.79 g/L after age 55 years. The influence of puberty, menopause, oral contraceptives, alcohol consumption, and morphometric characteristics was studied. Only being overweight by more than 20% statistically influenced LpAI values in men and in women. We used these results to select a reference population and to establish reference limits of LpAI at ages 25 to 35 years: 0.40-0.95 g/L for men and 0.46-1.05 g/L for women.
Multivariate interpretation of laboratory tests used in monitoring patients
Authors: Slotnick H B , Etzell P 
Published: January 2020

Abstract
This study demonstrates an approach to the problem of minimizing false-negative and false-positive laboratory findings. In this approach, we consider the fact that results of laboratory tests are correlated, utilize within-person test results to interpret current results, and minimize the impact of multivariate conservatism by examining test results in small groups. The procedure requires panels of tests to be divided into related subpanels, testing each subpanel independently, and using the Bonferroni inequality to determine whether any of the observed values for a given subpanel is "out-of-range." The procedure is demonstrated, and its limitations are observed and discussed.
Accuracy and precision of methods for theophylline measurement in physicians' offices
Authors: Cook J D , Platoff G E , Koch T R , Knoblock E C 
Published: January 2020

Abstract
We tested the accuracy and precision of five theophylline methods intended for use in physicians' offices. The Syntex AccuLevel, Ames Seralyzer, and 3M Diagnostics TheoFAST methods were less reproducible (CVs 6.3% to 9.2%) than the Abbott Vision and Kodak DT-60 (CVs 2.2% to 3.3%). Caffeine interfered with the Vision, Seralyzer, and AccuLevel methods, and theobromine interfered with the Vision, Seralyzer, and TheoFAST methods. Only the DT-60 method was free from interference from any of the 24 compounds tested. Results by all methods correlated well with those by the HPLC comparison method (Clin Chem 1981;27:1931-3) and by the Abbott TDx method for assay of 100 serum (or, when appropriate, paired whole-blood) samples. The frequency of sample results differing from the comparison method by greater than 2.0 mg/L was as follows: TDx, 11%; Vision (serum), 12%; Vision (whole blood), 18%; DT-60, 14%; AccuLevel, 18%; Seralyzer, 25%; and TheoFAST, 31%. The Kodak DT-60 method was the most nearly accurate and precise among these physician's office methods. Some physician's office methods for theophylline analysis are not adequate to guide dosage adjustments.
Evaluation of long-term frozen storage of plasma for measurement of high-density lipoprotein and its subfractions by precipitation
Authors: Nanjee M N , Miller N E 
Published: January 2020

Abstract
The concentration of high-density lipoprotein cholesterol (HDL-C) in plasma is now established as an independent risk factor for coronary heart disease, but more data are needed on the relative risk-predictive powers of different HDL subclasses. For epidemiologic and clinical purposes, isolation of HDL from other lipoproteins and separation of its two major subclasses, HDL2 and HDL3, are performed most conveniently by precipitation. Although storage of plasma is commonly necessary, little information is available on the long-term stability of HDL subclasses at different temperatures. Therefore, we quantified HDL-C, HDL2-C, and HDL3-C by dual precipitation with heparin-MnCl2/15-kDa dextran sulfate (H-M/DS) in samples of EDTA-plasma from 93 healthy subjects, after storage for one to 433 days at -20 degrees C, at -70 degrees C, or in liquid nitrogen (-196 degrees C). Fourteen samples (15%) were stored for a year or longer. At -20 degrees C, HDL-C decreased by 4.8% per year and HDL3-C decreased by 6.9% per year (P = 0.002 for both variables) relative to results obtained with samples stored in liquid nitrogen; total cholesterol, HDL2-C, and triglyceride did not change significantly at this temperature. When stored at -70 degrees C, none of the lipids showed any change relative to results obtained with liquid nitrogen. Thus, long-term storage of EDTA-plasma at -20 degrees C is unsuitable for subsequent quantification of HDL-C and its subclasses by H-M/DS dual precipitation. Storage at -70 degrees C is preferable, and is as reliable as storage in liquid nitrogen.
Evaluation of the RheumaStrip ANA profile test: a rapid test strip procedure for simultaneously determining antibodies to autoantigens U1-ribonucleoprotein (U1-RNP), Sm, SS-A/Ro, SS-B/La, and to native DNA
Authors: Paxton H , Bendele T , O'Connor L , Haynes D C 
Published: January 2020

Abstract
The "LipoGen RheumaStrip ANA Profile" test method (LipoGen, Inc.) is a new assay format for autoantibody detection in which recombinant autoantigens are used. This enzyme immunoassay, in test-strip format, detects antibodies to autoantigens U1-ribonucleoprotein (U1-RNP), Sm, SS-A/Ro, SS-B/La, and to native DNA (nDNA). We evaluated 200 antinuclear antibody (ANA)-positive and 100 ANA-negative sera for the presence of antibodies to U1-RNP, Sm, SS-A/Ro, SS-B/La, and nDNA by the new test-strip procedure. These data correlated well with those obtained with either Ouchterlony double immunodiffusion for U1-RNP, Sm, SS-A/Ro, and SS-B/La or with Crithidia luciliae indirect immunofluorescence for anti-nDNA. Assay sensitivity and assay specificity of the ANA Profile method as compared with those of established procedures were respectively as follows: 89.8% and 98.8% for U1-RNP, 86.4% and 95.3% for Sm, 97.9% and 89.3% for SS-A/Ro, 98.3% and 86.3% for SS-B/La, and 97.5% and 93.1% for nDNA. Agreement between the ANA Profile test and these other test methodologies ranged from 88.7% for the SS-B/La test to 97.3% for the U1-RNP test. This new test procedure substantially decreases the time and effort required to perform these assays. Total hands-on time and overall assay time were decreased by 72% and 97%, respectively.
Two new two-step immunoassays for free thyroxin evaluated: solid-phase radioimmunoassay and time-resolved fluoroimmunoassay
Authors: Nuutila P , Koskinen P , Irjala K , Linko L , Kaihola H L , Eskola J U , Erkkola R , Seppälä P , Viikari J 
Published: January 2020

Abstract
We measured concentrations of free thyroxin (FT4) in serum by using two new two-step FT4 assays--a solid-phase two-step radioimmunoassay. Spectria, and a time-resolved fluoroimmunoassay. Delfia--and compared the results with those by a two-step FT4 assay (RIA-gnost), a one-step FT4 analog assay (Amerlex-M), and FT4 measured after equilibrium dialysis. The new FT4 assays classified 30 hypothyroid and 43 hyperthyroid patients (untreated) well. In 138 patients with nonthyroidal illness (NTI) and in late pregnancy (n = 36), fewer subnormal FT4 values were reported by Spectria (P less than 0.001), Delfia (P less than 0.001), and RIA-gnost (P less than 0.01) than by Amerlex-M. The results of the Spectria and Delfia methods correlated with the results of the dialysis method (r = 0.76) in NTI patients and pregnancy, and were in better agreement with the clinical state than was FT4 by Amerlex-M. The FT4 values by Amerlex-M, but not by other methods, correlated with albumin concentration. We conclude that these new two-step methods present good alternatives for FT4 analysis.
Do enzymatic analyses of serum triglycerides really need blanking for free glycerol?
Authors: Jessen R H , Dass C J , Eckfeldt J H 
Published: January 2020

Abstract
Distributions of concentrations of free glycerol in clinical plasma obtained for triglyceride assay were compiled to determine the frequency with which increased concentrations of free glycerol posed a potential problem for clinical interpretation of triglyceride results. Clinical histories were studied in patients with increased concentrations of free glycerol to ascertain possible reasons for the increase and to assess the relative clinical importance of glycerol-blank-corrected triglyceride results. Significant increases in free glycerol were very uncommon, usually occurring in patients receiving glycerol-containing hyperalimentation fluids, those receiving heparin (which causes both in vivo and in vitro increases in free glycerol), or those critically ill. Free glycerol was never increased significantly in a large outpatient population. Monitoring lipid metabolism in critically ill patients, or measuring true triglyceride concentrations in patients receiving glycerol-containing fluids, may represent rare exceptions for which glycerol-blank correction is necessary for accurate clinical diagnosis and management. We conclude that there is insufficient justification for the routine expenditure of extra time and reagents to correct most analytical enzymatic triglyceride methods for free glycerol.
Determination of Inorganic Nitrate in Serum and Urine by a Kinetic Cadmium-Reduction Method
Authors: Cortas Najwa K , Wakid Nabll W 
Published: January 2020

Abstract
Nitrate in serum and urine was assayed by a modification of the cadmium-reduction method; the nitrite produced was determined by diazotization of sulfanilamide and coupling to naphthylethylene diamine. After samples were deproteinized with Somogyi reagent, the nitrate was reduced by Cu-coated Cd in glycine buffer at pH 9.7 (2.5 to 3 g of Cd granules for a 4-mL reaction mixture). The reduction followed pseudo-first-order reaction kinetics, a convenient time interval for assay being 75 to 90 min. Maximum reduction (85%) occurred at about 2 h. Detection limits in urine or serum were 2 to 250 µmol/L. This method does not require the reaction to go to completion, does not require expensive reagents or equipment, and can assay several samples simultaneously. Repeated assays of two serum pools gave CVs of 9.0% and 4.7% for nitrate concentrations of 31.4 and 80.2 µmol/L, nitrate was 1704.0 ± 1294 (SD) µmol/L (n = 21) in untimed normal urine, 81.8 ± 50.1 µmol/L in serum of 38 renal dialysis patients, and 51.2 ± 26.4 µmol/L in serum of 38 controls.
Deamidation of glutamine by increased plasma gamma-glutamyltransferase is a source of rapid ammonia formation in blood and plasma specimens
Authors: da Fonseca-Wollheim F 
Published: January 2020

Abstract
Owing to increased enzymatic hydrolysis of glutamine, additional ammonia is formed in blood and plasma specimens with increased gamma-glutamyltransferase activity (gamma-GT, EC 2.3.2.2.). The close correlation between gamma-GT and glutaminase (EC 3.5.1.2) activities (r = 0.97) in plasma, the inhibition with 6-diazo-5-oxo-L-norleucin or borate plus serine, and the activation with maleate clearly show that gamma-GT itself is the glutamine-deamidating enzyme in plasma. Under pathological conditions, increased gamma-GT activity can increase the rate of ammonia formation in plasma more than 30-fold the mean values of healthy subjects. Increased in vitro formation of ammonia caused by increased gamma-GT activity is an important source of false-positive findings in ammonia determination. Because of the high prevalence of pathological gamma-GT activities in clinical populations, blood specimens for ammonia analysis should be preserved by addition of borate plus serine.
Optimized fluorometric determination of urinary delta-aminolevulinic acid by using pre-column derivatization, and identification of the derivative
Authors: Okayama A , Fujii S , Miura R 
Published: January 2020

Abstract
We previously reported the usefulness of a fluorometric method to determine urinary delta-aminolevulinic acid (ALA) concentrations by using post-column derivatization to monitor the effect of lead exposure. We have further improved the method by introducing pre-column derivatization by using reaction of ALA with acetylacetone and formaldehyde. Response of the hematopoietic system to lead exposure can now be easily detected at blood lead concentrations as low as 162 micrograms/L. The fluorescent ALA derivative, a new aromatic product, 2-methylideneamino-3,5-diacetyl-4,6-dimethylphenylpropionic acid, is separated on octadecyl silica column by high-performance liquid chromatography and the fluorescence intensity is detected with a fluorophotometer. Sample recoveries for 12 urine samples from workers exposed to lead and unexposed controls were 91.9-110.2%. The results obtained by the pre-column derivatization method agreed with those by the post-column derivatization method. The new method increases the sensitivity to a detection limit to 10 micrograms of delta-aminolevulinic acid per milliliter of urine and is simple enough to be used for routine monitoring of the biological effect of exposure to low concentrations of lead.
Impact of new technologies on health-care costs and on the nation's "health"
Authors: Massaro T A 
Published: January 2020

Abstract
By virtually all criteria, the American health-care system has the largest and most widely distributed technology base of any in the world. The impact of this emphasis on technology on the cost of care, the rate of health-care inflation, and the well-being of the population is reviewed from the perspective of the patient, the provider, and the public health analyst.
Integrating laboratory robots with analytical instruments--must it really be so difficult?
Authors: Kramer G W 
Published: January 2020

Abstract
Creating a reliable system from discrete laboratory instruments is often a task fraught with difficulties. While many modern analytical instruments are marvels of detection and data handling, attempts to create automated analytical systems incorporating such instruments are often frustrated by their human-oriented control structures and their egocentricity. The laboratory robot, while fully susceptible to these problems, extends such compatibility issues to the physical dimensions involving sample interchange, manipulation, and event timing. The workcell concept was conceived to describe the procedure and equipment necessary to carry out a single task during sample preparation. This notion can be extended to organize all operations in an automated system. Each workcell, no matter how complex its local repertoire of functions, must be minimally capable of accepting information (commands, data), returning information on demand (status, results), and being started, stopped, and reset by a higher level device. Even the system controller should have a mode where it can be directed by instructions from a higher level.
Preventing ascorbate interference in ion-chromatographic determinations of urinary oxalate: four methods compared
Authors: Petrarulo M , Marangella M , Bianco O , Marchesini A , Linari F 
Published: January 2020

Abstract
In an attempt to decrease ascorbate interference on the ion-chromatographic determination of urinary oxalate, we compared the effectiveness of four different methods for ascorbate elimination by analyzing a representative urine pool supplemented with successive ascorbate additions. Two of the methods--treatment with ferric ions or boric acid--have been described elsewhere; treatments with nitrites or ascorbate oxidase (EC 1.10.3.3) are investigated here as possible alternatives. Consideration of the main features, advantages, and drawbacks of the four procedures leads us to conclude that boric acid dilution is a good routine method and that pre-incubation with ascorbate oxidase reliably prevents ascorbate interference in assays of urinary oxalate.