bluuebunny/crossref_metadata_2025_split huggingface dataset:
Concentrations of total and free dehydroepiandrosterone in plasma and dehydroepiandrosterone in saliva of normal and hirsute women under basal conditions and during administration of dexamethasone/synthetic corticotropin
Authors: Swinkels L M , Ross H A , Smals A G , Benraad T J 
Published: January 2020

Abstract
Using a specific and sensitive radioimmunoassay involving extraction with diethyl ether and chromatographic separation of steroids, we measured concentrations of salivary and plasma dehydroepiandrosterone (DHEA) in 22 women with normal ovulatory cycles (ages 18-45 years). Salivary DHEA values closely correlated with total and free DHEA in plasma. In the follicular phase the mean concentrations of salivary and plasma free DHEA were virtually equal [mean (SD): 0.61 (0.32) and 0.56 (0.34) nmol/L, respectively]. In the luteal phase, salivary DHEA slightly exceeded the plasma free DHEA [0.68 (0.40) vs 0.56 (0.38) nmol/L, P less than 0.01]. Also, during combined dexamethasone/synthetic corticotropin administration in 25 patients with androgenizing disorders and in 10 normal subjects (each in the follicular and luteal phases), the concentration of DHEA in saliva strongly correlated with total and free DHEA in plasma. During these dynamic tests, the mean concentrations of free DHEA in plasma and salivary DHEA in the hirsute women were significantly higher than the mean concentrations in the control women at all times before and after corticotropin infusion (P less than 0.05- less than 0.0001). In contrast, plasma total DHEA in patients exceeded nonhirsute values only at 15 min after corticotropin administration. In six of 25 patients total DHEA during combined administration of dexamethasone/synthetic corticotropin exceeded normal values by at least 2 SD. The response of salivary and free DHEA to synthetic corticotropin in this subgroup was also excessive.
Fluorometric determination of carnitine in serum with immobilized carnitine dehydrogenase and diaphorase
Authors: Matsumoto K , Yamada Y , Takahashi M , Todoroki T , Mizoguchi K , Misaki H , Yuki H 
Published: January 2020

Abstract
A fluorometric flow-injection method for determining carnitine with use of immobilized enzymes carnitine dehydrogenase (EC 1.1.1.108) and diaphorase (EC 1.8.1.4) was developed and applied to the assay of carnitine in serum of patients treated with valproic acid. After fractionation and hydrolysis of carnitines in serum samples by perchloric acid and potassium hydroxide, liberated carnitine was converted to resorufin by immobilized carnitine dehydrogenase and diaphorase in the presence of beta-NAD+ (1.0 mmol/L), resazurin (12.5 mumol/L), and Tris acetate (0.6 mol/L, pH 9.0) at 37 degrees C. The fluorescence intensity of resorufin was monitored at lambda Ex 560 nm and lambda Em 580 nm. The calibration curve was linear for carnitine amounts from 0.1 to 1.0 nmol. Quantitative analytical recovery and satisfactory within- and between-run imprecision of carnitine in each carnitine fraction were obtained. Interference by bilirubin, serum albumin, and hemoglobin was negligible. Carnitine deficiencies were detected in about 20% of the valproic acid-treated patients (n = 198). The present method should be useful for monitoring carnitine deficiencies in clinical laboratories.
Diagnosis of ectopic pregnancy by the rate of increase of choriogonadotropin in serum: diagnostic criteria compared
Authors: Emancipator K , Bock J L , Burke M D 
Published: January 2020

Abstract
We compare three methods for using the rate of change of human choriogonadotropin (hCG) concentration in serum to diagnose ectopic pregnancy. With Method I, the lower limit for the rate of increase of serum hCG in normal pregnancy is 66% per 48 h. With Method II, a different lower limit of normal is specified for each of four discrete sampling intervals of hCG. With Method III, the lower limit of normal is determined by a continuous discriminant function of the initial hCG concentration. If the initial hCG concentration is less than or equal to 2000 int. units/L (Second International Standard), all three methods have acceptable diagnostic efficiencies, and there are no statistically significant differences among conclusions from the methods. None of the three methods performs satisfactorily if the initial hCG concentration is greater than 2000 int. units/L. We recommend Method I because it is simpler than the other two.
Proficiency testing for creatine kinase isoenzyme CK-2 (CK-MB) in Ontario
Authors: McQueen M J , Patten R L , Henderson A R , Krishnan S , Wood D E , Webb S 
Published: January 2020

Abstract
Three surveys of the measurement and interpretation of creatine kinase (CK; EC 2.7.3.2) isoenzyme 2 (CK-MB) were conducted in Ontario, Canada, in 1989. Of the clinical laboratories participating, 66% used immunological methods and 24% used electrophoretic methods. Although reference ranges and interpretative routines varied widely, 95% of the laboratories reported correct interpretations for 10 of the 15 vials tested. The only major problems occurred with samples with very low total CK activity. Within-survey duplicate results compared well, and 89% of the laboratories had consistent between-survey results, even for specimens with low total CK activity. Errors were proportional to the frequency of use of the different analytical methods. The lyophilized testing material gave higher results with methods for measuring the mass of CK-2, suggesting that the material contained inactive but immunologically intact CK-2. The surveys indicate that laboratories should review their protocols for measuring CK-2 when only a single sample from the patient is available.
Simplified fluorometric assay of total selenium in plasma and urine
Authors: Sheehan T M , Gao M 
Published: January 2020

Abstract
We describe here a single-tube assay that may be applied to the whole range of selenium status in adult and pediatric patients, including depletion during parenteral or other nutrition. A specimen or aqueous standard, 100 microL, is digested with 0.5 mL of HNO3/HCIO4 (4/1 by vol, at 190 degrees C for 90 min), reduced with 0.5 mL of concentrated HCI (150 degrees C, 30 min), and complexed with 0.5 mL of 6.3 mmol/L 2,3-diaminonaphthalene (DAN) reagent in the presence of EDTA (60 degrees C, 30 min). The resulting fluorophore is extracted into cyclohexane and its fluorescence measured (excitation at 366 nm; emission at 544 nm). It is not necessary to control pH during the complexing step or to protect the DAN from light. The limit of detection of selenium is 10 micrograms/L (0.126 mumol/L); linearity of results extends to 2000 micrograms/L (25.3 mumol/L). Between-batch precision is 5%, analytical recovery 90%-96%. Performance is good as tested against Reference Materials and by participation in a National Quality Assurance Scheme.
Centrifugal ion-selective electrode system for potassium in whole blood
Authors: Brackett J , Durley B , Janczak R , Kazlauskas V , Kmiec J , Norlie J , Rosencranz R , Schultz S , Spring T , Theusch W 
Published: January 2020

Abstract
We describe a novel ion-selective electrode (ISE) system that can be used in the Abbott Vision analyzer. A reusable sensor pack and a disposable test pack have been miniaturized to approximately the size and weight of a conventional Vision test pack, thus eliminating the need for a separate ISE module. The sensor pack contains a fluid path, battery-powered electronics, and screw-in electrodes. The test pack contains separate chambers and fluid channels for a blood specimen and two aqueous calibrators. During a run, plasma is separated from blood cells and is moved sequentially, along with the two calibrators, into and out of the sensor pack by centrifugal force. Each run includes checks for electromechanical integrity, fluid contamination, calibration slope and intercept, and specimen hemolysis. The system operates with CVs of less than 2% and gives results that correlate well with those by flame photometry and direct ISE methods. Either skin-puncture or venipuncture whole blood can be assayed, as well as serum or plasma.
Rhabdomyolysis secondary to lovastatin therapy
Authors: Manoukian A A , Bhagavan N V , Hayashi T , Nestor T A , Rios C , Scottolini A G 
Published: January 2020

Abstract
We report a case of lovastatin-induced rhabdomyolysis and resulting life-threatening renal failure. Lovastatin, a hypocholesterolemic agent, decreases endogenous cholesterol synthesis by inhibiting 3-hydroxy-3-methylglutaryl coenzyme A reductase (EC 1.1.1.88). This agent has been implicated in causing rare serious side effects in various clinical settings; however, the mechanism of these adverse reactions is not understood. The clinical course of our patient was characterized by profound muscle weakness with marked increases in serum creatine kinase and myoglobin. Light- and electron-microscopic studies of skeletal muscle of our patient demonstrated a noninflammatory myopathy suggestive of ongoing rhabdomyolysis with vacuolization and focal degeneration of myocytes. The patient's symptoms and the laboratory values referable to rhabdomyolysis resolved after discontinuation of the drug. We speculate that the rhabdomyolysis was due to mitochondrial damage secondary to inadequate synthesis of coenzyme Q and heme A, members of the electron-transport system of the inner mitochondrial membrane.
Testicular cancer secretes intact human choriogonadotropin (hCG) and its free beta-subunit: evidence that hCG (+hCG-beta) assays are the most reliable in diagnosis and follow-up
Authors: Saller B , Clara R , Spöttl G , Siddle K , Mann K 
Published: January 2020

Abstract
Human choriogonadotropin (hCG) and free hCG-beta values for 934 serum samples from patients with seminomatous or nonseminomatous testicular cancer were measured by highly specific immunoradiometric assays (IRMAS). In non-seminoma samples, hCG and hCG-beta were highly correlated (r = 0.82, P less than 0.001). Of 112 "marker-positive" seminoma samples, only 46 (41.1%) showed both increased hCG and hCG-beta. In 39 cases (34.8%) only hCG-beta and in 27 cases (24.1%) only dimer-hCG was increased. This makes the determination of hCG and hCG-beta, either by two assays or by a single hCG (+hCG-beta) assay, most reliable in these patients. For all samples, hCG (+hCG-beta) was measured by a polyclonal RIA and a monoclonal IRMA, which differed in their cross-reactivities with hCG-beta (234% and 720%, respectively). The hCG (+hCG-beta) IRMA, as a result of its higher hCG-beta cross-reactivity, was superior to the hCG (+hCG-beta) RIA in detecting slightly increased hCG-beta. Additionally, 11 widely used commercial hCG kits were tested for their hCG-beta cross-reactivities and showed values between less than 3% and 264%.
SCC antigen measured in malignant and nonmalignant diseases
Authors: Molina R , Filella X , Torres M D , Ballesta A M , Mengual P , Cases A , Balaque A 
Published: January 2020

Abstract
SCC antigen was measured in the serum of 214 patients with benign diseases and in 251 patients with various cancers. With 2.5 micrograms/L as the upper normal limit for serum, values were positive in 2.9% of 69 healthy subjects (I), 29.0% of 214 patients with benign pathologies (II), and 41% of 217 patients with active cancer (III). The highest values in group II were for patients in renal failure (64%) or with lung diseases (40%) or head-and-neck diseases (21.2%). Specificity of SCC increased (91.1%) when we excluded patients in renal failure or with creatinine values greater than 133 mumol/L. In group III, SCC values were abnormal in 57.7% of patients with squamous cell carcinoma, but in only 9.3% of those with other histological types (P less than 0.001). In squamous cell carcinoma of the lung, cervix, or head and neck, SCC values were related to tumor stage, values being highest in patients with metastases.
3-Hydroxy-3-methylglutaryl-CoA lyase deficiency as detected by radiochemical assay in cell extracts by thin-layer chromatography, and identification of three new cases
Authors: Gibson K M , Lee C F , Kamali V , Johnston K , Beaudet A L , Craigen W J , Powell B R , Schwartz R , Tsai M Y , Tuchman M 
Published: January 2020

Abstract
In this rapid radiochemical assay for 3-hydroxy-3-methylglutaryl-coenzyme A lyase (I) activity in cell extracts, DL-3[glutaryl-3-14C]hydroxy-3-methylglutaryl-coenzyme A is used as substrate and the radiochemical product, [3-14C]acetoacetic acid, is converted to the more stable [3-14C]-3-hydroxybutyric acid in the presence of added NADH and 3-hydroxybutyrate dehydrogenase. Substrate and product are separated and quantified by thin-layer chromatography on cellulose (solvent system: butanol/water/formic acid, 77:13:10 by vol). All reagents for the assay are commercially available. No detailed column chromatography or spectrophotometry is required. Thus the assay is suited for any clinical laboratory. Using this procedure, we studied cultured fibroblasts or lymphocytes isolated from whole blood from five patients in whom the urinary organic acid profile was suggestive of deficiency of I. Three patients had less than or equal to 18% of control I activity in fibroblast or lymphocyte extracts. The other two had activity within the normal range. In one of the latter cases, urinary excretion of three of the characteristic acids disappeared with age, and 3-hydroxyisovaleric acid excretion was within normal limits. The other case presented with urinary excretion of moderate amounts of all four metabolites and the characteristic absence of urinary ketone bodies. Evidently, confirmatory enzyme studies should be undertaken, even when the profile of urinary organic acids appears definitive for this deficiency.
Increased activities of cytosol aminopeptidase and lactate dehydrogenase in serum originate from lymphocytes in necrotizing lymphadenitis
Authors: Sugaya N , Kanno T , Nirasawa M , Mitamura K , Takeuchi Y , Osano M 
Published: January 2020

Abstract
In three pediatric patients with necrotizing lymphadenitis, cytosol aminopeptidase activity (c-AP; EC 3.4.11.1) in serum was markedly increased to 509, 417, and 191 U/L, respectively (normal range 25-60 U/L). Lactate dehydrogenase (LD; EC 1.1.1.27) was also increased, with LD-3 predominating. The increased concentrations of c-AP and LD presumably originated from the destruction of infected, activated lymphocytes, especially T lymphocytes. Necrotizing lymphadenitis is probably caused by a lymphocytotropic virus.
Calibration in three dimensions: optimizing a two-parameter calibration technique to extend the range of an immunoturbidimetric urinary albumin assay into antigen excess
Authors: Tillyer C 
Published: January 2020

Abstract
I describe a general technique, called "two-parameter calibration," which allows precise determination of analyte from non-monotonic calibration plots and the calibration of immunoturbidimetric assays in antigen excess. Using three-dimensional calibration plots and relative-sensitivity curves, two optimal parameters may be selected from a number of possible options by using criteria presented here. Choosing two different values of delta At1-t2, the change in absorbance from time t1 to t2--as the reaction parameters in an immunoturbidimetric assay for albumin, I have optimized the choice of time interval for two-parameter calibration and extended the working range of the assay by three- to fourfold. The albumin assay shows excellent agreement of observed and expected values (r = 0.996) and also with results of a routine kinetic dye-binding method used on diluted plasma samples (r = 0.970).
"Microgel diffusion blotting" for sensitive detection of antibodies to extractable nuclear antigens
Authors: De Keyser F , Verbruggen G , Veys E M , Nimmegeers J , Schatteman L , Goethals K , Vandenbossche M 
Published: January 2020

Abstract
A fast immunoblotting procedure, termed "microgel diffusion blotting," is used to detect and identify antibodies to extractable nuclear antigens (i.e., to Sm, RNP, and SSB) in patients with rheumatic diseases. The method differs from the standard immunoblotting techniques by the use of ultra-thin microgels for polyacrylamide gel electrophoresis: the very thin gel layer allows transfer of proteins to a nitrocellulose membrane by simple diffusion. Principal advantages of this variant technique are its simplicity, rapidity, and reproducibility--characteristics that make the test suitable for routine application. We compared the sensitivity of the test with that of double immunodiffusion in agarose for the evaluation of humoral antinuclear immunity. Microgel diffusion blotting detected antibodies in serum at concentrations less than 0.001 of those detectable by immunodiffusion.
Mitochondrial aspartate aminotransferase determined by "Fast Protein Liquid Chromatography"
Authors: Grøstad M , Rej R , Huseby N E 
Published: January 2020

Abstract
We describe an improved separation of the isoenzymes of aspartate aminotransferase (EC 2.6.1.1), based on ion-exchange chromatography. Involving the "Fast Protein Liquid Chromatography" system (Pharmacia) with a MonoQ column, this rapid, reproducible method for quantifying the mitochondrial enzyme shows good resolution and sensitivity, and results correlate well with those by an established immunochemical method.
Evaluation of determination of lactate dehydrogenase isoenzyme 1 by chemical inhibition with perchlorate or with 1,6-hexanediol
Authors: Paz J M , Garcia A , Gonzales M , Treviño M , Tutor J C , Jaquet M , Rodriguez-Segade S 
Published: January 2020

Abstract
We have evaluated the determination of lactate dehydrogenase (EC 1.1.1.27) isoenzyme 1 activity by chemical inhibition of the other isoenzymes with perchlorate and with 1,6-hexanediol. In the hexanediol method, we studied the effect of the duration of incubation with the inhibitor; a 5-min incubation yielded results closest to those of an immunochemical technique (Isomune-LD). The perchlorate method was the most precise, and the hexanediol method the least, although for none of the techniques did the coefficient of variation exceed the medically acceptable limit prescribed by the College of American Pathologists. Pairwise correlation among the immunoprecipitation, electrophoretic, and chemical inhibition methods was good (r greater than 0.991), although the differences between means were statistically significant (except for the comparison of the two chemical inhibition methods). Because of its ease, low cost, and precision, we recommend the perchlorate method for routine use.
Effects of lyophilization of serum on the measurement of apolipoproteins A-I and B
Authors: Marcovina S M , Adolphson J L , Parlavecchia M , Albers J J 
Published: January 2020

Abstract
A common accuracy-based standardization program is indispensable for establishing reference intervals for the clinical use of apolipoproteins. The development and distribution of reference materials and quality-control materials that do not exhibit matrix effects between methods is essential to the standardization process. We examined the suitability of lyophilized material as a common reference material for the measurement of apolipoproteins A-I and B. We determined values for apolipoproteins A-I and B in frozen and lyophilized serum pools, using different immunochemical approaches. We found little or no differences in apolipoprotein A-I values between frozen and lyophilized pools as determined by the different methods. In contrast, values for apolipoprotein B in lyophilized samples were consistently lower than those obtained for frozen samples. After adjusting for the effect of dilution due to reconstitution, the difference in the apolipoprotein B values for lyophilized as compared with frozen samples ranged from -26% to 4%, depending upon the assay method. Evidently, serum pools in lyophilized from are not a suitable matrix for reference materials for apolipoprotein B measurements but can be used for apolipoprotein A-I measurements.
Radioimmunoassay of type I collagen that mainly detects degradation products in serum: application to patients with liver diseases
Authors: Hartmann D J , Trinchet J C , Ricard-Blum S , Beaugrand M , Callard P , Ville G 
Published: January 2020

Abstract
This radioimmunoassay for type I collagen mainly detects degradation products of the molecule in human serum samples. Type I collagen antigenicity in serum can be separated into two peaks by gel-filtration chromatography. The larger form represents collagen molecules (as shown by immunoblotting experiments), and (or) type I collagen with aminoterminal propeptide or intact procollagen molecules. The smaller form, the exact nature of which is not known, is quantitatively the principal antigenic form and is derived from degradation of type I collagen. The concentration of type I collagen in serum is increased mainly in cirrhotic patients, with or without active liver disease, but also somewhat in alcoholic patients without cirrhosis.
Ultraviolet-absorbing organic anions in uremic serum separated by capillary zone electrophoresis, and quantification of hippuric acid
Authors: Schoots A C , Verheggen T P , De Vries P M , Everaerts F M 
Published: January 2020

Abstract
Organic anions accumulated in blood serum of patients with chronic renal failure were separated by a novel technique: closed-system capillary zone electrophoresis (CZE) in a pH6 carrier-electrolyte system. Hippuric acid (HA), p-hydroxyhippuric acid, and uric acid were identified by their co-elution with standards prepared in ultrafiltered normal serum and by comparison with the corresponding ultraviolet-detected peaks positively identified in the HPLC analyses. Analysis time for the entire profile is 8 min. Repeatabilities (CVs) of CZE migration times and peak areas of the three acids in serum samples were about 0.7% and 6%, respectively. We quantified HA in 10 ultrafiltered uremic serum samples and compared results with those by a previously described HPLC procedure. The very good agreement further supports the identification of hippuric acid. Accuracy and precision of the CZE method were similar to those for the HPLC gradient-elution method, but analysis time for HA (8 min) is much less than by HPLC (90 min). Our technique is very suitable for selective, rapid analysis for (ultraviolet-absorbing) anionic constituents in ultrafiltered uremic serum, without any sample pretreatment.
Rapid, robust method for measuring low concentrations of albumin in urine
Authors: Medcalf E A , Newman D J , Gorman E G , Price C P 
Published: January 2020

Abstract
We describe a rapid particle-enhanced turbidimetric immunoassay for albumin in urine. Intra- and interassay CVs were less than 5% and less than 10%, respectively, the detection limit is 2 mg/L, and the working range extends to 200 mg/L. Mean analytical recovery of albumin added to centrifuged urines was 100% (SD 10.6%), and, when results were compared with those by the Pharmacia RIA, the correlation coefficient was 0.99. The working reagents are stable for at least six months; thus this assay is suited for both batch and urgent analysis.
Immunoadsorption of IgG onto second antibody covalently attached to Amino-Dylark beads for radioimmunoassays
Authors: Kakabakos S E , Evangelatos G P , Ithakissios D S 
Published: January 2020

Abstract
We present a solid-phase immobilization method for radioligand assays, using an immunoadsorption coating procedure of anti-triiodothyronine rabbit IgG (anti-T3 IgG) onto second antibody (sheep anti-rabbit IgG) covalently bound to Amino-Dylark beads. The second antibody was in excess, compared with the first antibody, thus eliminating reproducibility problems between immunoadsorptions. Beads coated with second antibody can be used to immobilize a variety of antigen-specific first antibodies. The amount of anti-T3 antibody required for solid-phase T3 radioimmunoassay (RIA) was only 10% more, per assay tube, than that utilized in liquid-phase T3 RIA, in which polyethylene glycol solution was the separation reagent; characteristics of assay performance were comparable. The immobilization procedure requires high-titer antisera or antigen-specific IgG and seems advantageous because of the decrease in antibody requirements without significant modification of antibody functionality.