bluuebunny/crossref_metadata_2025_split huggingface dataset:
Micro-analysis for quinidine in serum by thin-layer chromatography followed by fluorescence densitometry.
Authors: Kelner M , Bailey D N 
Published: January 2020

Abstract
We report a thin-layer-chromatographic micro-analysis for quinidine in serum, with detection by fluorescence densitometry. Quinidine is extracted from 20 microL of serum at pH 13 into 3 mL of hexane/acetone solution (80/20 by vol) containing N-(1-naphthyl)ethylenediamine as internal standard. The extract is concentrated and applied to silica-gel-impregnated plates for conventional thin-layer chromatography. Quinidine is identified from its RF value and quantified from the peak-height ratio between quinidine and the internal standard, relative to that of simultaneously extracted serum standards. The proposed assay is sensitive (to 0.2 mg/L), specific for unmetabolized quinidine, precise (between-run coefficients of variation less than 6%), and readily adaptable to large-scale "batch" analysis. Peak-height ratio is linearly related to concentration to at least 20 mg/L. Quinidine concentrations in the serum of patients, as measured by the proposed method (x) and by a traditional double-extraction spectrofluorometric assay (y), were related as follows: y = 0.994x + 0.276 (r = 0.989, n = 20).
Limited usefulness of the proportion of tests with normal results in review of diagnostic services utilization.
Authors: Eisenberg J M , Williams S V 
Published: January 2020

Abstract
We tested the hypothesis that the proportion of normal results in tests ordered by a physician correlates directly with the proportion of tests that are disapproved by a utilization review audit for inappropriate test use. Auditors reviewed 3497 charts for 13 067 repeated determinations of 10 diagnostic tests ordered by 81 medical residents to determine if test use had been appropriate, according to explicit criteria. By the Pearson product-moment correlation coefficient, there was a significant (p less than 0.001) correlation between the proportion of normal results in tests ordered by residents and the residents' audit-disapproval rates, a previously undocumented relationship. Although statistically significant, the correlation coefficient of 0.25 means that the proportion of normal tests results predicted only 6% of the variance in the audit-disapproval rates. This relationship is not strong enough to use the proportion of normal results as a measure of a physician's inappropriate test use, except to select physicians for utilization review.
Diagnostic efficacy of newer synthetic-substrates methods for assessing coagulation variables: a critical overview.
Authors: Fareed J , Messmore H L , Walenga J M , Bermes E W 
Published: January 2020

Abstract
With the introduction of synthetic substrates, many newer methods have been developed for testing coagulation parameters. Some of these methods are used in clinical settings, and many have been evaluated for their diagnostic efficacy in various coagulation disorders. Clinical chemistry laboratory instrumentation has been used to accommodate these methods. Commercially available kits for antithrombin III, heparin, plasminogen, alpha 2-antiplasmin, and factor X are used by many laboratories. Individual reagents have also become available and are being used to develop assays for routine diagnostic use. The development of suitable standards is rapidly underway, and their availability will facilitate adoption of these methods by hospital laboratories. Many of the synthetic-substrate-based assays that have been introduced for routine diagnostic purposes have been published recently. Here, we provide an overview of the newer amidolytic methods for the measurement of certain coagulation variables.
Inborn errors of steroid biosynthesis: detection by a new mass-spectrometric method.
Authors: Shackleton C H 
Published: January 2020

Abstract
A new mass-spectrometric technique relies on ionization during bombardment of the analyte (dissolved in a liquid matrix, usually glycerol) by an atom beam (e.g., Ar0, Xe0). This technique, termed "fast atom bombardment," is particularly useful in the characterization of polar charged molecules. A neutral beam is not essential, and a primary beam of cesium ions has been successfully used to produce spectra equivalent to those obtained by fast atom bombardment. In this communication I report data on the use of both ion and atom primary beams for producing secondary-ion mass spectra of conjugated steroids. In negative-ion spectra produced for steroid glucuronides and sulfates, the ion [M - H]- is invariably the major high-mass peak, and the lack of substantial fragmentation allows assay of relatively complex mixtures if the analytes differ in mass. I describe here the use of secondary-ion mass spectrometry for distinguishing, by urinary steroid analysis, patients with the four enzyme defects that can affect cortisol synthesis: defects in 17 alpha-hydroxylase, 3 beta-hydroxysteroid dehydrogenase/isomerase, 21-hydroxylase, and 11 beta-hydroxylase.
Assessment of the benzethonium chloride method for routine determination of protein in cerebrospinal fluid and urine.
Authors: Flachaire E , Damour O , Bienvenu J , Aouiti T , Later R 
Published: January 2020

Abstract
We have tested the characteristics of the method of Iwata and Nishikaze (Clin Chem 25: 1317, 1979). The linearity, sensitivity, and precision are satisfactory and the reactivity of benzethonium chloride with various proteins (albumin, immunoglobulins) is the same. The method has been compared with Meulemans's technique (Clin Chim Acta 5: 757, 1960), routinely used in our laboratories, by analysis of 82 samples of cerebrospinal fluid (CSF) and 119 samples of urine. Our results for cerebrospinal fluid agree well with those of Iwata and Nishikaze (r = 0.976; y = 0.992x - 0.013), but we find their method unsuitable for urinary protein determination, probably because of interfering compounds in urine.
Enzyme immunoassay for urinary albumin.
Authors: Fielding B A , Price D A , Houlton C A 
Published: January 2020

Abstract
We describe an enzyme-linked immunosorbent assay for urinary albumin, performed on microtiter plates with use of commercially available antisera and peroxidase conjugate. The assay range is 3-1000 micrograms/L, the sensitivity 625 pg. The method is suitable for measurement of albumin excretion in either normal or pathological urine. For 20 normal children, the range of urinary albumin excretion was 1.7-22.9 mg/24 h.
Ion-chromatographic measurement of oxalate in unprocessed urine.
Authors: Menon M , Mahle C J 
Published: January 2020

Abstract
We describe a sensitive, simple technique for determining urinary oxalate. Urine, diluted as necessary with distilled water, is injected into an ion chromatograph. Oxalate is detected conductimetrically as a distinct peak near the tail of the chromatogram. This peak specifically represents oxalate, because it is abolished if the sample is treated with oxalate decarboxylase. We have used this technique to measure oxalate in more than 3000 consecutively received urine samples. It has a CV of 6%.
Immunoglobulin-complexed aspartate aminotransferase.
Authors: Weidner N , Lott J A , Yale V D , Wahl R L , Little R A 
Published: January 2020

Abstract
We report two cases of unexplained, isolated, persistently increased aspartate aminotransferase activity in serum. In the first patient, this lasted for 10 years and prompted multiple hospitalizations and medical/surgical consultations. For patient two, the abnormal enzyme activity resulted in hospitalization for further evaluation of possible heart disease. In spite of extensive investigation to determine the possible reason for the abnormality, no clear clinical cause was ever discovered in either patient. Electrophoretic and immunologic evidence indicates that the enzyme was complexed to IgG in the serum of both individuals. Recognition that this complex is probably benign may obviate other patients having to undergo unnecessary hospitalization, anxiety, and expense.
Increased urinary excretion of free 20 alpha- and 20 beta-dihydrocortisol in a hypercortisolemic but hypocortisoluric patient with Cushing's disease.
Authors: Schöneshöfer M , Weber B , Nigam S 
Published: January 2020

Abstract
We identified non-metabolized, non-conjugated 20 alpha- and 20 beta-dihydrocortisol (20 alpha- and 20 beta-DHF) in urine from a patient with Cushing's disease, by use of three different liquid-chromatographic systems and by gas chromatography-mass spectrometry. We document that these 20-isomers of dihydrocortisol may strongly contribute to unspecific interferences with the immunological assessment of urinary free cortisol (F). The urinary excretion rates of 20 alpha- and 20 beta-DHF were quantified radioimmunologically with use of a cross-reacting cortisol antiserum after effective purification by liquid chromatography. The patient with Cushing's disease had mean peripheral cortisol concentrations of 1018 nmol/L. The urinary excretion rates (nmol/24 h) were 1455 for 20 alpha-DHF, 330 for 20 beta-DHF, and 18 for F. The corresponding reference values (median in nmol/24 h) were 174 for 20 alpha-DHF, 111 for 20 beta-DHF, and 68 for F (n = 22). We conclude that (a) specific estimation of urinary free F is not as highly sensitive for diagnosis of chronic hypercortisolemic states as is generally assumed; and (b) measurement of urinary free 20 alpha- and 20 beta-DHF or of the corresponding 20-DHF:F ratios may be more sensitive.
Some considerations of methodology and standardization of apolipoprotein B immunoassays.
Authors: Rosseneu M , Vercaemst R , Steinberg K K , Cooper G R 
Published: January 2020

Abstract
Apolipoprotein B, the major protein component of very-low-density (VLDL) and low-density (LDL) lipoproteins in serum, is being widely measured in serum, to help assess risk of cardiovascular disease. Standardization has proven difficult because of the physical and immunochemical heterogeneity of LDL and VLDL, the masking of antigenic determinants of LDL and VLDL, the insolubility of apolipoprotein B, the instability of lipoprotein reference materials, and the multiplicity of analytical methods. Here we have examined the literature and collected current information from lipoprotein scientists to determine the problems--and the ways investigators have attempted to solve them--in preparation, storage, and use of standards and anti-apolipoprotein B sera, analytical procedures and reagents, and the nature of apolipoprotein B in serum. Standardization appears possible with development of stable reference materials that are applicable to the various analytical methods, controlled immunochemical reaction conditions, and establishment of a selected interim reference method for use as a point of reference.
2,6-Dimethyloctanedioic acid--a metabolite of phytanic acid in Refsum's disease.
Authors: Greter J , Lindstedt S , Steen G 
Published: January 2020

Abstract
The urine of two patients with Refsum's disease consistently contained 2,6-dimethyloctanedioic acid, a compound not normally found in human urine. In addition, their urines contained increased concentrations of 3-methylhexanedioic acid. These two compounds may be formed from phytanic acid by an initial omega-oxidation and subsequent beta-oxidations. It was calculated that this oxidation pathway may metabolize at least 30 mg of phytanic acid per day.
Kinetic assay of human pepsin with albumin-bromphenol blue as substrate.
Authors: Gray S P , Billings J A 
Published: January 2020

Abstract
A novel substrate, albumin complexed with bromphenol blue, has been developed for the assay of human gastric juice pepsin by a kinetic method in the Cobas centrifugal analyzer. The action of pepsin on the complex degrades the albumin and releases the dye. The change in the color of the substrate is a zero-order reaction. Human and porcine pepsin have different Km's with the new substrate. This kinetic method has a throughput of 28 tests in approximately 10 min and good precision (CV = 2.0%). Other advantages are analysis in homogeneous solution (thereby eliminating the need to separate substrate and products), lack of interference from bilirubin or phenol red, and the expression of pepsin activity in IUB enzyme units.
Effect of aspirin on determinations of glycosylated hemoglobin.
Authors: Nathan D M , Francis T B , Palmer J L 
Published: January 2020

Abstract
We investigated the in vivo and in vitro effects of aspirin on several clinical assays of glycosylated hemoglobin. Acetylation of hemoglobin falsely increased the glycosylated hemoglobin fraction measured by "high-performance" liquid chromatography and electrophoresis, but isoelectric focusing and colorimetric techniques differentiated between acetylated and glycosylated fractions. Aspirin ingestion may result in an apparent increase in glycosylated hemoglobin measured with common clinical assays.
Simultaneous very fast liquid-chromatographic analysis of ethosuximide, primidone, phenobarbital, phenytoin, and carbamazepine in serum.
Authors: Kabra P M , Nelson M A , Marton L J 
Published: January 2020

Abstract
We describe a sensitive, specific, and very fast liquid-chromatographic assay for simultaneously determining five anticonvulsants (ethosuximide, primidone, phenobarbital, phenytoin, and carbamazepine) by using commercially available 5- or 3-microns particle size reversed-phase columns and a microflow-cell-equipped ultraviolet detector. The anticonvulsant drugs are extracted from 200 microL of serum containing 50 mg of cyclopal per liter as an internal standard, by elution from a Bond-Elut (Analytichem International, Harbor City, CA 90710) column with 300 microL of methanol. A 5-microL aliquot of the eluate is applied to an analytical column and eluted with a mobile phase of acetonitrile/methanol/phosphate buffer, 20 mmol/L, pH 3.7 (13.5/35/51.5 by vol), at a flow rate of 3.0 mL/min and at 50 degrees C. Detection is at 210 or 195 nm. The chromatography is complete in less than 2.5 min with the 5-microns-particle column, and in less than 1.4 min with the 3-microns-particle column. The sensitivity of the method for all drugs is less than 1 mg/L. Analytical recovery of drugs added to serum ranged from 92 to 109% for concentrations up to 200 mg/L. Between-run precision (CV) ranged from 1.3 to 4.1%.
Radioimmunoassay of bile acids in tissue, bile, and urine.
Authors: Wildgrube H J , Stockhausen H , Metz P , Mauritz G , Mahdawi R 
Published: January 2020

Abstract
Two commercially available (Abbott Labs.) radioimmunoassays for determination of conjugated cholic acid and sulfoglycolithocholic acid in serum have been modified for bile acid measurements in alcoholic tissue extracts, bile, and urine. The specificity of both radioimmunoassays has been determined with regard to 27 free and conjugated bile acids. After filtration, bile acids can be measured in urine and bile without prior extraction. Tissue is homogenized and the bile acids are extracted into methanol. Urinary excretion by 64 healthy humans was 2.09 (SD 1.09) mumol of conjugated cholic acid and 8.44 (SD 8.03) mumol of sulfated glycolithocholic acid per 24 h. In liver from 10 patients with various noncholestatic liver disease, the mean concentration of conjugated cholic acid was 32.4 (SD 15.9) nmol/g wet weight. In the liver of 27 male Wistar rats, the concentration of conjugated cholic acid was 41.3 (SD 11.7) nmol/g of tissue, of sulfoglycolithocholic acid 5.1 (SD 2.3) nmol/g of tissue.
Suitability of control materials in the differential inhibition assay for human pancreatic and salivary amylase.
Authors: O'Donnell M D , McGeeney K F 
Published: January 2020

Abstract
We investigated the behavior of 26 quality-control sera with the inhibitor method for differential amylase (EC 3.2.1.1) assay. We also studied the sensitivity to the wheat-derived inhibitor of pancreatic amylases from 10 different animals in comparison with human pancreatic and salivary amylase. The results indicate that only control materials containing human amylases can be measured accurately. The animal amylases (bovine, equine, porcine) used in many quality control sera are relatively insensitive to the inhibitor as compared with human pancreatic and salivary amylase.
Liquid-chromatographic profiles of urinary porphyrins.
Authors: Schreiber W E , Raisys V A , Labbé R F 
Published: January 2020

Abstract
Information on changes in the urinary excretion pattern of porphyrins can be especially useful in the diagnosis of disorders of porphyrin metabolism. Most clinical laboratory procedures are designed for assay of uroporphyrin and coproporphyrin only, and in many cases even these are not cleanly separated. Hence, we developed a "high-performance" liquid-chromatographic procedure to separate and quantify all five urinary porphyrins--that is, those with four through eight carboxyl groups. Before chromatography, the porphyrins are isolated from other urinary components by two simple, rapid pretreatment steps, then injected into the chromatograph in nonesterified form. They are separated and eluted with a step gradient of methanol/phosphate buffer, pH 3.0, in which the methanol content is first 650, then 850 mL/L. As little as 1 ng of eluted porphyrins can be measured fluorometrically. Analytical recovery of coproporphyrin is virtually 100% and of uroporphyrin 75-80%. CVs are about 10% for coproporphyrin at 70 micrograms/L and 20-40% for uroporphyrin at 8 micrograms/L.
Alpha-fetoprotein concentrations in maternal serum: relation to race and body weight.
Authors: Crandall B F , Lebherz T B , Schroth P C , Matsumoto M 
Published: January 2020

Abstract
We confirmed the relation between maternal weight and serum alpha-fetoprotein concentration and have shown a further relation--to ethnic origin. Of these two, maternal weight is the more closely related. Oriental, white, and Hispanic women showed no significant differences in serum AFP concentrations when corrections for maternal weight were applied. Black women showed consistently higher values, by an average of 10% at each week of gestation. These corrections only affected values falling just above or below the 95th centile cutoff. We conclude that corrections for maternal weight and race should be applied when values for alpha-fetoprotein in maternal serum are being interpreted.
Sensitivity and specificity of the hydrogen breath-analysis test for detecting malabsorption of physiological doses of lactose.
Authors: Rosado J L , Solomons N W 
Published: January 2020

Abstract
We examined the changes in sensitivity and specificity that would occur with alterations in the sample-collection schedule and (or) cutoff criterion for the increase in hydrogen concentration in breath after administration of doses of lactose in the dietary range. In a breath-analysis test to classify individuals as lactose-absorbers or lactose-malabsorbers, 41 subjects drank 360 mL of intact cow's milk, containing 18 g of lactose, and breath samples were collected and analyzed at 30-min intervals for 5 h. An increase in H2 concentration of greater than or equal to 20 microL/L above basal values at any of the 10 intervals was diagnostic of malabsorption. Increases of greater than or equal to 18 or greater than or equal to 15 microL/L were only 85% as specific in classifying the same individuals. Reduction in the number of samples tested per subject uniformly reduced the sensitivity. However, a simplified procedure suitable for field studies (in which four samples--at 0, 2, 3, and 4 h--are collected and analyzed with greater than or equal to 20 microL/L as the cutoff value) gives 80% sensitivity and 100% specificity, as compared with the 11-sample procedure.
The "eyetone" blood glucose reflectance colorimeter evaluated for in vitro and in vivo accuracy and clinical efficacy.
Authors: Hay W W , Osberg I M 
Published: January 2020

Abstract
We evaluated the performance of a blood glucose reflectance colorimeter ("Eyetone," Ames Co.) for accuracy and precision with use of "Dextrostix" (Ames Co.) glucose oxidase reagent strips for blood samples with known and unknown concentrations of glucose covering the usual range of neonatal blood glucose (200-800 mg/L). The meter was calibrated and tested by research nurses and one clinical chemist. Five unknowns were tested for accuracy and precision (56-92 determinations per unknown) and compared with Beckman Astra values (plasma and calculated whole blood). Eyetone/Dextrostix values differed (gave lower values) from the calculated whole-blood values only at concentrations less than 300 mg/L. On 258 clinical specimens from newborn infants, Eyetone/Dextrostix values were not different from calculated whole-blood values (p less than 0.05, r = 0.80). Operator training to develop a consistent procedure was the most critical factor in achieving accurate and precise results.
An evaluation of four serum tests for pregnancy.
Authors: Ryder K W , Munsick R A , Oei T O , Young P C , Blackford H F 
Published: January 2020

Abstract
We evaluated four pregnancy tests (Biocept-G, Beta-CG, Preg/Stat, and HCG-Beta Screen), using sera from 59 nonpregnant subjects and 77 patients with serum human choriogonadotropin beta-subunit (beta-hCG) concentrations ranging from 4 to 100 000 int. units/L. The results obtained for each test were compared with the results predicted on the basis of the sample's beta-hCG concentration and the beta-hCG concentration the manufacturer claimed necessary for a positive result (the test's analytical sensitivity). Biocept-G had the best sensitivity (100%), specificity (98.9%), and accuracy (99.2%). Beta-CG had the poorest sensitivity (86.4%), Preg/Stat the poorest specificity (87.5%), and accuracy (92.6%). We confirmed the manufacturer's claimed analytical sensitivity (200 int. units/L) for the Biocept-G procedure, but our calculated analytical sensitivity for the other tests was significantly different from that claimed by their manufacturers. Best results were obtained with Biocept-G, but with its analytical sensitivity of 200 int. units/L, samples from early pregnancy will give negative results. None of the pregnancy tests evaluated here will establish the presence or absence of early pregnancy with certainty.
Immunonephelometry of specific proteins in human seminal plasma.
Authors: Lizana J , Blad E 
Published: January 2020

Abstract
Using immunonephelometry, we measured albumin, transferrin, alpha 1-antitrypsin, orosomucoid, hemopexin, IgG, IgA, and secretory IgA in seminal plasma of men who were attending a fertility clinic. Seminal plasma, obtained by centrifugation of semen, is a turbid liquid producing high blank values that were not diminished by ultracentrifugation, filtration, or treatment with protamine, dextran sulfate, or various lipidophilic gels. Pretreatment of seminal plasma with polyethylene glycol 6000 (final concentration, 40 g/L) considerably decreased the blank values without appreciably changing the relative concentration of the eight proteins studied. Our investigations illustrate the feasibility of this application of immunonephelometry. This approach can be a valuable diagnostic tool in the laboratory evaluation of the male partner in infertile unions.