bluuebunny/crossref_metadata_2025_split huggingface dataset:
Two-dimensional electrophoresis of human plasma apolipoproteins.
Authors: Sprecher D L , Taam L , Brewer H B 
Published: January 2020

Abstract
The two-dimensional electrophoretic method with silver staining we describe better resolves plasma apolipoproteins (apo) than any procedure previously described. It can be used to screen for abnormalities in apoA-I, apoA-II, apoA-IV, apoC-II, apoC-III, apoD, apoE, and apoH. In addition, this is the first presentation of apoD and apoH on two-dimensional gels. This electrophoretic method will permit the quantification of plasma apolipoproteins by computer imaging. Such detailed analysis of the plasma apolipoproteins should provide a better understanding of apolipoprotein function and the role these apolipoproteins play in lipoprotein metabolism and the pathophysiology of dyslipoproteinemias and coronary artery disease.
Pouring reproducible gradients in gels under computer control: new devices for simultaneous delivery of two independent gradients, for more flexible slope and pH range of immobilized pH gradients.
Authors: Altland K , Altland A 
Published: January 2020

Abstract
Recently we described (Electrophoresis 5: 143-147, 1984) a new device for producing density and solute gradients, involving computer-controlled coöperation of stepmotor-driven high-precision burettes, the purpose being to substantially improve reproducibility, flexibility, and documentation of gradients used in gels and in other applications in biochemistry. Here we present the functional principle of three modified and partly alternative devices, based on simultaneous delivery of a density gradient and a non-density gradient. They provide unlimited flexibility of choice for the slope of the non-density gradient, which is stabilized by the density gradient. They seem especially useful for pouring immobilized pH gradients in gels of wide pH ranges (between pH 3.5 and 10) where localized flattening of the gradient is needed to selectively improve resolution. Used in two-dimensional electrophoretic analysis, they should considerably improve control of spot coördinates, standardization of the technique, and interlaboratory data exchange.
Direct solid-phase fluoroenzymeimmunoassay of 5 beta-pregnane-3 alpha, 20 alpha-diol-3 alpha-glucuronide in urine.
Authors: Shah H , Saranko A M , Härkönen M , Adlercreutz H 
Published: January 2020

Abstract
A competitive solid-phase fluoroenzymeimmunoassay has been developed for rapidly measuring 5 beta-pregnane-3 alpha, 20 alpha-diol-3 alpha-glucuronide (Pd-3G) directly in diluted specimens of pre-breakfast urine. The assay involves use of an antiserum to Pd-3G and enzyme-labeled antigen prepared by chemically linking glucose-6-phosphate dehydrogenase (EC 1.1.1.49) to Pd-3G. Antibody-bound and free antigen are separated by use of a solid-phase double antibody: sheep anti-rabbit gamma-globulin coupled to cellulose particles. The solid phase, isolated by centrifugation, is washed free of labeled antigen and endogenous enzyme interferences. Enzyme activity in the bound fraction is then measured fluorometrically with glucose 6-phosphate as the substrate and generated NADPH as a fluorogenic indicator of enzyme activity. The assay is sufficiently sensitive (30-35 pg per assay tube), specific, and reliable for routine use, and results correlate well (r = 0.98) with those by an established specific radioimmunoassay. Because it is suited to routine use, this assay may be applied to detecting ovulation, assessing the function of corpus luteum, and monitoring early pregnancy.
Continuous-flow determination of primary bile acids, by bioluminescence, with use of nylon-immobilized bacterial enzymes.
Authors: Roda A , Girotti S , Ghini S , Grigolo B , Carrea G , Bovara R 
Published: January 2020

Abstract
We describe a continuous-flow bioluminescence method for measuring primary bile acid in serum, with nylon as the solid support. 7 alpha-Hydroxysteroid dehydrogenase (EC 1.1.1. 159), a bacterial luciferase (EC 1.14.14.3), and NAD+:FMN oxido-reductase (EC 1.6.8.1) are covalently co-immobilized on a nylon coil (1 m X 1.0 mm i.d.). The assay is highly specific for 7 alpha-hydroxy bile acids. Other bile acids and steroids do not interfere. The continuous-flow light-emitting system, in which the reactor (nylon coil) is placed in front of a photomultiplier tube inside a luminometer, is versatile and simple. The flow is air-segmented, and serum samples (5-50 microL) can be injected directly. Concentration and response are linearly related from 10 to 2500 pmol per assay tube. The precision of the method is satisfactory (CV 5-10%), both inter- and intra-assay. We validated the technique by comparing results with those by RIA, enzyme immunoassay, and "high-performance" liquid chromatography. More than 20 samples an hour can be analyzed, with no carryover. The nylon-immobilized enzymes are stable for more than two months, and greater than 500 samples can be analyzed with use of a few milligrams of enzymes. Normal values for bile acid content of serum ranged from 1 to 2.5 mumol/L, in agreement with those obtained by other methods.
Enzyme-linked immunosorbent microassay and hemagglutination compared for detection of thyroglobulin and thyroid microsomal autoantibodies.
Authors: Roman S H , Korn F , Davies T F 
Published: January 2020

Abstract
We have evaluated for their potential use in the routine clinical laboratory enzyme-linked immunosorbent assays (ELISA) for human thyroglobulin antibodies (hTg-Ab) and microsomal antibodies (M-Ab). Results are expressed in terms of an "ELISA Index," based on comparison with a laboratory standard. The specificity of both ELISA assays is shown by dose-dependent inhibition of the hTg-Ab and M-Ab activities of the laboratory standards by the appropriate specific antigens. Similar concentrations of ovalbumin had no significant effect on the standard activity in both assays. For consecutive samples evaluated for hTg-Ab (n = 113) and M-Ab (n = 106) by ELISA and hemagglutination, rank order analysis of the results showed a highly significant correlation between the methods (r = 0.81, p = less than 0.001 for hTg-Ab; r = 0.82, p = less than 0.001 for M-Ab). However, 8/47 (17%) of samples positive in the hTg-Ab ELISA were negative by hemagglutination, and 7/69 (12%) of samples positive in the M-Ab ELISA were negative by hemagglutination. We effectively excluded the possibility of false positivity of these specimens by ELISA by blocking specimen positivity with the specific antigens in 12 of 14 specimens investigated. We conclude that ELISA techniques for human thyroid autoantibodies are sensitive and specific, easy to initiate, objective, and capable of use in large-scale screening. They are superior to standard hemagglutination techniques by having an increased detection rate for hTg-Ab and M-Ab.
Characterization of apparent lactate dehydrogenase isoenzyme 6: a lactate-independent dehydrogenase.
Authors: Podlasek S J , McPherson R A , Threatte G A 
Published: January 2020

Abstract
We found in a prospective study of lactate dehydrogenase isoenzyme 6 (LD6) in human tissues obtained at autopsy that LD6 was usually present in liver when death was preceded by prolonged hypotension or impaired ventilation but not in cases of sudden death. Other organs containing LD6 were kidney and spleen. LD6 is heat stable, differs from H-subunit-containing LD isoenzymes by pyruvate resistance, differs from M-subunit-containing LD isoenzymes by immunoprecipitation, and is distinct from spermatic LDX. LD6 from liver extracts acted without lactate as substrate and could be enhanced by ethanol added to the substrate. These results indicate that LD6 is not a true lactate dehydrogenase, and that it frequently appears in severe liver injury.
Methods for extracting phospholipids from human amniotic fluid compared.
Authors: Duck-Chong C G , Baker G J , Murdoch S R , Price R M 
Published: January 2020

Abstract
Phospholipids were extracted from human amniotic fluid by various procedures, including the two most commonly applied to amniotic fluid for evaluation of fetal lung maturity. We find that the yield of phospholipid is greatly procedure dependent. This should be taken into account when one is considering the various reported methods of evaluating fetal lung maturity, because in some of them phospholipid data are expressed in terms of absolute concentration in the amniotic fluid. There were also significant differences in phospholipid composition in extracts prepared by the various procedures, but in general these were not large enough to influence evaluation of fetal lung maturity by methods in which phospholipid data are expressed in relative terms, as ratios or percentages--e.g., in the lecithin/sphingomyelin ratio and "lung profile" procedures. In the extraction method originally recommended for determination of the lecithin/sphingomyelin ratio, both the yield and composition of phospholipid depend on the extent of mixing.
Rapid quantification of pentobarbital in serum by fluorescence polarization immunoassay.
Authors: Li P K , Lee J T , Schreiber R M 
Published: January 2020

Abstract
The commercially available fluorescence polarization immunoasay (FPIA) method for phenobarbital is demonstrated to be useful in the quantification of pentobarbital in serum. The effective range for the method is 1.0 to 80.0 mg/L. The method is simple, precise, and fast. The application of the method is limited to patients receiving pentobarbital as the only barbiturate. The FPIA is recommended for use in clinical laboratories when a rapid estimation of pentobarbital is required in monitoring patients undergoing high-dose pentobarbital therapy.
Interconversion and comparison of the results of three methods for cholinesterase in serum.
Authors: Newman M A , Que Hee S S 
Published: January 2020

Abstract
We investigated three methods for determination of cholinesterase (ChE) in human blood sera, using reference sera, sera of known ChE content, and serum variously diluted with deactivated sera. The methods were the Du Pont aca analyzer, the Pfizer "ChE-tel" method, and the Michel method with and without direct reagent-blank correction. With respect to precision and reproducibility the methods ranked: aca greater than Michel method corrected directly for reagent pH changes (Michel) greater than ChE-tel method greater than Michel method corrected indirectly for reagent pH changes. The interrelationships derived, in terms of each method's individual units were: Michel = (0.054 +/- 0.001) aca - (0.043 +/- 0.086), r2 = 0.947 ChE-tel = (4.44 +/- 0.30) aca - (5.11 +/- 0.99), r2 = 0.959 ChE-tel = (80.2 +/- 5.8) Michel + (0.028 +/- 0.240), r2 = 0.947 The ChE-tel method was subject to variations due to the quality of different kits. The aca results were validated by a collaborative laboratory study. Sera of known activity can be used effectively for accurate calibration.
Adaptation of EMIT reagents to the Cobas Bio centrifugal analyzer.
Authors: Hamlin C R , Sullivan P A 
Published: January 2020

Abstract
Our adaptation of EMIT enzyme immunoassay reagents to the Cobas Bio centrifugal analyzer avoids the decrease in precision at the upper end of the therapeutic range reported in other adaptations. Long-term (12-month) CVs for lidocaine, valproic acid, and tobramycin were 5% or less; for quinidine, acetaminophen, and phenytoin, long-term CVs ranged from 7.2% to 8.6%.
Improved liquid-chromatographic determination of mexiletine, an antiarrhythmic drug, in plasma.
Authors: Mastropaolo W , Holmes D R , Osborn M J , Rooke J , Moyer T P 
Published: January 2020

Abstract
In this improved reversed-phase liquid-chromatographic procedure for determination of mexiletine in plasma, mexiletine and an internal standard, chlorodisopyramide, are extracted with methylene chloride from 0.5 mL of serum or plasma; the extract is then concentrated and injected onto a C18 chromatographic column. Mexiletine in the column effluent is detected by monitoring absorbance at 210 nm. It is quantified by use of mexiletine-internal standard peak-height ratios. The relation between this ratio and mexiletine concentration is linear from 0.1 to 5.0 mg/L. The lower limit of detection is about 50 micrograms/L. At a mexiletine concentration of 2.0 mg/L in serum, intrarun precision (CV) is 2.9% and inter-run precision is 5.9%; at 0.5 mg/L, these CVs are 5.7% and 9.6%, respectively. Analytical recovery of added mexiletine in serum is 68-88%. Therapeutic concentrations of some commonly administered drugs in patients' specimens did not interfere. In serum from 38 patients receiving mexiletine for cardiac arrhythmia, concentrations measured by this method correlated with therapeutic efficacy.
Hyponatremia: a diagnostic problem.
Authors: Walmsley R N , White G H 
Published: January 2020

Abstract
Hyponatremia, a common clinical problem, may result from a wide variety of causes. Treatment can vary from fluid restriction to rehydration, depending on the pathogenesis of the disorder. Essential to evaluation of hyponatremic patients is correct estimation of the status of the extracellular fluid volume, because this determines the type of therapy: a patient who is hypovolemic will not benefit from fluid restriction; a euvolemic patient should not be "rehydrated." To distinguish between these two conditions requires a searching history and clinical examination, including measurement of the blood pressure both while the subject is standing and lying. Not all patients with the classical biochemical features of the syndrome of inappropriate secretion of vasopressin (low plasma [Na+] and osmolality, high urinary [Na+] and osmolality) will have the disorder, because these same features may also be present in other hyponatremic disorders, including hypovolemic hyponatremia.
Colorimetry of hemoglobin in plasma with 2,2'-azino-di(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS).
Authors: Takayanagi M , Yashiro T 
Published: January 2020

Abstract
Hemoglobin in plasma can be determined by the color-developing action of 2,2'-azino-di(3-ethylbenzthiazoline-6-sulfonic acid), which is oxidized to a colored form by a peroxidase-like effect of hemoglobin in the presence of hydrogen peroxide. Sensitivity, precision, and accuracy are discussed. The calibration curve is linear for hemoglobin concentrations up to 1 g/L; the minimum detectable concentration is 20 mg/L. The within-run precision (CV) was 2.39%, analytical recovery 101.8%. Interference from plasma proteins and lipids was eliminated by centrifuging the reaction mixture before measuring its absorbance at 410 nm.
Normal reference-intervals for 20 biochemical variables in healthy infants, children, and adolescents.
Authors: Gómez P , Coca C , Vargas C , Acebillo J , Martinez A 
Published: January 2020

Abstract
We determined normal reference values from data on sera of 2099 outpatient children (ages one week to 14 years) at our institution. Using a continuous-flow instrument (SMAC, Technicon), we determined the following analytes in each serum sample: glucose, creatinine, uric acid, inorganic phosphorus, sodium, potassium, chloride, total CO2, iron, cholesterol, triglycerides, total protein, albumin, total bilirubin, creatine kinase, lactate dehydrogenase, alkaline phosphatase, aspartate aminotransferase, alanine aminotransferase, and calcium. The resulting data were coded and subsequently processed in an IBM 370 computer, and the reference values (3rd and 97th percentiles) were defined for each analyte. A two-way analysis of variance was also done to determine the influence of age and sex on results of these 20 biochemical tests.
Quantification of nonenzymically glycated albumin and total serum protein by affinity chromatography.
Authors: Yatscoff R W , Tevaarwerk G J , MacDonald J C 
Published: January 2020

Abstract
We have evaluated an affinity-chromatographic procedure for determination of glycated albumin (GA) and glycated total serum protein (GSP). Recovery of these analytes was inversely related to free glucose concentration, thus necessitating removal of free glucose. For this we used molecular-exclusion chromatography on G-25 Sephadex, or dialysis, the latter procedure resulting in significantly (p less than 0.05) lower concentrations of GSP and GA. Total protein concentration and percent glycation are also inversely related, and so protein concentrations must be standardized before the assay. Within- and between-run CVs for both GSP and GA were less than 6.5 and 18%, respectively, the determination of GA being generally the more precise of the two. Labile glycated fractions, lipemia, icterus, hemolysis, and type of anticoagulant did not affect the results, but assay temperature did. Diabetic subjects showed substantially higher concentrations of GA and GSP than did normal subjects. Because of the life span of these analytes in circulation, their measurement may provide a short-term index of glycemic control.
Some factors affecting determination of carotenoids in serum.
Authors: Mathews-Roth M M , Stampfer M J 
Published: January 2020

Abstract
Because of increasing interest in carotenoid pigments, we conducted a study of the methods of determining carotenoids in serum. We found 1 mol of KOH per liter of absolute methanol to be the most effective saponifying solution. The absorbance of beta-carotene in petroleum ether, the extraction solvent, is proportional to dilution up to an absorbance of 0.85 at 450 nm. Beta-carotene in petroleum ether solution is not impracticably sensitive to ambient light at room temperature. However, if vitamin A is also to be measured in these serum specimens or petroleum ether extracts, exposure to light should be minimized. We found that serum may be shipped either in cold packs or at ambient temperature (tested up to five days) without significant change in carotenoid concentration. Serum samples for carotenoid determination are best stored at -70 degrees C: samples stored at -20 degrees C deteriorate substantially over several months.
Liquid-chromatographic determination of eight tri- and tetracyclic antidepressants and their major active metabolites.
Authors: Sutfin T A , D'Ambrosio R , Jusko W J 
Published: January 2020

Abstract
A "high-performance" liquid-chromatographic method is presented for monitoring the therapeutic concentrations, in plasma, of eight tri- and tetracyclic antidepressants (amitriptyline, nortriptyline, imipramine, desipramine, doxepin, clomipramine, maprotiline, and protriptyline) and their major active metabolites. One of two internal standards is added to 0.5 mL of drug-containing plasma, the pH is adjusted to about 9.5 with borate buffer, and the sample is extracted with isoamyl alcohol in hexane. The extracts are chromatographed on a column of silica and absorbance of the effluent is measured at either 214 or 254 nm. Chromatographic response is linearly related to concentration for all components over a 5-500 ng range. Analytical recovery of the drugs and metabolites from plasma is approximately 75 to 85% at low and high concentrations. Within-run and day-to-day precision (CV) is less than 5% for both high and low concentrations of most of these drugs and metabolites. Parallel analysis of clinical samples by gas chromatography indicates that results by the two techniques are comparable. We report some results of therapeutic monitoring of clinical samples.
Effects of residual liquid junction potential in direct potentiometry of potassium.
Authors: Winkelman J W , Merritt C , Scott W J , Kumar A , Baum G 
Published: January 2020

Abstract
To further the accurate direct potentiometry of plasma electrolyte concentrations, we investigated the effects of solution composition on the residual liquid junction potential (RLJP) during measurement of K+. Assuming that the binding constant between K+ and proteins or bicarbonate is no greater than with Na+, we calculate that the amount of bound K+ can be neglected. A significant RLJP exists between simple solutions containing Na+, K+, and Cl- ions and solutions containing Na+, K+, Cl-, and HCO3- ions. Replacing Cl- with HCO3- leads to an increase in the RLJP, which in turn contributes to a negative error in K+ analysis. A small decrease in RLJP is observed as the ionic strength is increased. The Henderson equation gives a reasonable estimate of the magnitude of the observed RLJP, even though the liquid junction does not meet the conditions under which the equation is rigorously applicable. Errors attributed to RLJP may be substantially minimized by using a calibrator solution that contains an anion with mobility similar to that of HCO3-.
Urea, creatinine, and glucose determined in plasma and whole blood by a differential pH technique.
Authors: Ripamonti M , Mosca A , Rovida E , Luzzana M , Luzi L , Ceriotti F , Cottini F , Rossi-Bernardi L 
Published: January 2020

Abstract
We report the conditions (buffer composition and enzyme activity) required for estimating three frequently determined analytes--urea, glucose, and creatinine--by use of an improved version of the differential pH apparatus previously described (Clin Chem 29: 80-85, 1983). For each analyte, we used only one specific enzyme, thus avoiding a chain of auxiliary and indicator reactions. The method requires about a minute for each determination in undiluted plasma or whole blood.
Values for some serum analytes in high-risk infants, two days postpartum.
Authors: Fitzsimons E J , Fletcher M A , Chakrin A 
Published: January 2020

Abstract
Using a continuous-flow (Technicon SMAC) analyzer, we measured the concentration of 20 analytes in capillary blood sera from 149 neonates in an intensive-care unit. Included were term and pre-term babies, both groups with and without asphyxia. The values obtained, especially for those enzymes and analytes that are related to renal function, offer baseline data against which the effect of therapeutic and physiological changes can be evaluated.
Complexes of serum gamma-glutamyltransferase with apolipoproteins and immunoglobulin A.
Authors: Artur Y , Wellman-Bednawska M , Jacquier A , Siest G 
Published: January 2020

Abstract
We have detected complexes between gamma-glutamyltransferase and apolipoproteins or immunoglobulin A in sera from patients with hepatobiliary diseases but not in sera from healthy individuals. An average of 52.4% of the enzymic activity was precipitated by antiserum against apolipoprotein A, 29.9% by antiserum against apolipoprotein B, and 9.7% by antiserum against immunoglobulin A. Fifty to 60% of the enzyme activity was inhibited in the immunoprecipitates from the transferase fraction bound to apolipoprotein A or immunoglobulin A, and 21% in the fraction bound to apolipoprotein B. We identified the complexed transferase fractions by electrophoresis.
Homogeneous luminescence immunoassay for total estrogens in urine.
Authors: Messeri G , Caldini A L , Bolelli G F , Pazzagli M , Tommasi A , Vannucchi P L , Serio M 
Published: January 2020

Abstract
We describe an homogeneous luminescence immunoassay for "total" estrogens in enzymically hydrolyzed urine from nonpregnant women. The antiserum, raised against estriol-16,17- dihemisuccinate conjugated to bovine serum albumin, specifically bound the C-19 steroids carrying the estrogen-characteristic phenolic group. 17 beta-Estradiol conjugated with aminobutylethyl isoluminol was used to monitor the immunological reaction; this conjugate was stable for at least two years. Because binding to the antiserum markedly enhances the light-producing efficiency of the tracer, no separation of bound and free antigen is necessary. Results (microgram/24 h) by this method (y) correlated well (r = 0.958) with those by a conventional fluorometric (x) method (y = 2. 51x - 2.83). The sensitivity (detection limit) is 4 micrograms/L and the precision compares well with that of commonly used RIA methods. The method appears suited to large numbers of samples, as in menstrual cycle monitoring.