bluuebunny/crossref_metadata_2025_split huggingface dataset:
Human conjugated bilirubin--isolation, biosynthesis, and direct molecular characterization.
Authors: Wu T W , Zumbulyadis N , Gross S , Gohlke R S 
Published: January 2020

Abstract
We prepared human conjugated bilirubin by isolation from fresh gall bladder bile and by biosynthesis using liver homogenates. The isolation protocol was modified after Lucassen (doctoral thesis, Univ. Utrecht, 1961), and the in vitro synthesis was done with fresh liver homogenates in the presence of D-glucaro-1,4-lactone (a glucuronidase inhibitor). From direct analyses of these preparations with 270-MHz proton nuclear magnetic resonance and field-desorption mass spectrometry, we deduced that a major conjugated bilirubin species in bile is a diglucuronide, whereas in liver biosynthesis it is a diconjugate containing glucuronic acid and possibly glucuronolactone co-esterified to the bilirubin backbone. If the glucuronolactone is indeed present in the native biosynthetic material, we do not know whether it derives from glucuronic acid and, if so, whether lactonization occurs before or after the acid has been esterified to form the conjugate.
Melanoma detection by enzyme-radioimmunoassay of L-dopa, dopamine, and 3-O-methyldopamine in urine.
Authors: Faraj B A , Lawson D H , Nixon D W , Murray D R , Camp V M , Ali F M , Black M , Stacciarini W , Tarcan Y 
Published: January 2020

Abstract
This enzyme-radioimmunoassay for the measurement of L-dopa, dopamine, and 3-O-methyldopamine is based on the incubation of urine in the presence of catechol-O-methyltransferase, aromatic-L-amino-acid decarboxylase, and S-adenosylmethionine. The O-methylated dopamine metabolite formed, 3-O-methyldopamine, was characterized by radioimmunoassay. To evaluate the role of L-dopa metabolism in melanoma, we used the enzyme-radioimmunoassay to assess concentrations of L-dopa, dopamine, and 3-O-methyldopamine in urine from 10 healthy subjects, 10 hospitalized patients without melanoma and 28 patients with different degrees of melanoma. The effect of surgery for melanoma on urinary output of these catechols of melanoma patients was also evaluated. No significant difference in urinary L-dopa, dopamine, and 3-O-methyldopamine excretion rates was seen between normal subjects (L-dopa 1.3 +/- 0.3, dopamine 147 +/- 38, and 3-O-methyldopamine 31.4 +/- 13.6 microgram/24 h), hospitalized patients without melanoma, and amelanotic melanoma patients. However, the excretion rates for these metabolites in melanotic melanoma (L-dopa 5.6 +/- 1.2, dopamine 555 +/- 121, and 3-O-methyldopamine 178 +/- 40.3 microgram/24 h) were significantly (p &lt; 0.005) higher than in control or amelanotic melanoma subjects. After surgery, there was a substantial decrease in urinary output of L-dopa and its metabolites by these patients.
Gas-chromatographic assay for thiopental in plasma, with use of a nitrogen-specific detector.
Authors: Jung D , Mayersohn M , Perrier D 
Published: January 2020

Abstract
An accurate, sensitive, and specific gas-liquid-chromatographic procedure is described for determining concentrations of thiopental in human plasma. After a double extraction of 0.2 or 1.0 mL of plasma containing phenobarbital as an internal standard, thiopental and the internal standard are derivatized in a polar non-aqueous solvent system with iodomethane. The reaction mixture is then evaporated, the residue reconstituted with ethyl acetate, and 20 microL injected into a 3% OV-17 column of a gas chromatograph equipped with a nitrogen-phosphorus detector. Linearity and reproducibility over the concentration range 25 microgram/L to 10 mg/L in plasma are excellent. The sensitivity and wide range of linearity exhibited by this method permit thorough characterization of the disposition of thiopental after the usual induction doses of 3-4 mg/kg of body weight.
Direct quantitation of glycosaminoglycans in 2 mL of urine from patients with mucopolysaccharidoses.
Authors: Burlingame R W , Thomas G H , Stevens R L , Schmid K , Moser H W 
Published: January 2020

Abstract
Glycosaminoglycans in urine from patients representing the major different mucopolysaccharidoses were separated and measured by use of a procedure that requires only 2 mL of urine. The compounds were resolved by two-dimensional electrophoresis on cellulose acetate plates and made visible by staining with Alcian Blue. They were identified by co-migration with standard glycosaminoglycans, by digestion with specific glycosidases, and by specific degradation with HNO2. They were quantitated by comparing the absorbance of eluates of the stained spots to appropriate standard curves for each glycosaminoglycan. This study revealed additional findings. About half of the patients excreted small amounts of heparin. Further, the keratan sulfate in samples from Morquio's disease patients migrated differently from authentic keratan sulfate unless digested with chondroitinase ABC. Our results for these diseases are in harmony with earlier reports.
Optimizing determination of plasma albumin by the bromcresol green dye-binding method.
Authors: Robertson W S 
Published: January 2020

Abstract
Some modifications of the conditions of the reaction between plasma and bromcresol green have led to an improved method for determination of plasma albumin with the Vickers M300 multichannel analyzer. Dye concentration and reaction time are the factors principally influencing method specificity, but variable protein composition of human plasma also affects it, so that optimal reaction conditions vary from specimen to specimen. Thus a compromise must be reached such that the best conditions for determining plasma albumin over a range of different protein concentrations are achieved. In the proposed method for the Vickers M300 a reaction time of 12 s (the minimum possible) is used. Comparison with "rocket" immunoelectrophoresis gave the following linear regression: y = 10 + 0.79 x (n = 91; r = 0.96).
The "ultra-free" ultrafiltration technique compared with equilibrium dialysis for determination of unbound thiopental concentrations in serum.
Authors: Jung D , Mayersohn M , Perrier D 
Published: January 2020

Abstract
We compare a new ultrafiltration technique, involving a unique Millipore membrane, with the classical method of equilibrium dialysis for determining the fraction of thiopental not bound to serum proteins. This fraction, as determined by equilibrium dialysis at 37 degrees C, ranged between 12 and 16% for total concentrations at 50 microgram/L to 10 mg/L of serum. In contrast, ultrafiltration at 37 degrees C yielded a 49% higher value for unbound thiopental: 26.3 (SD 2.6)%. Determined at room temperature (24 degrees C), there was no statistically significant difference for results by the two methods: 14.2 and 15.9%, respectively. The discrepancy between results at 37 degrees C may partly be explained by serum proteins penetrating the Ultra-Free filter. For the routine clinical measurement of unbound drug concentrations, the ultrafiltration membrane at room temperature appears to be sufficiently accurate and less time-consuming than equilibrium dialysis.
Sensitive and specific radioimmunoassay for creatine kinase BB isoenzyme in serum, with use of an autoantibody.
Authors: Urdal P , Kierulf P 
Published: January 2020

Abstract
We have developed an equilibrium radioimmunoassay for creatine kinase BB (CK-BB) isoenzyme in serum. We used as antibody a CK-BB binding immunoglobulin G isolated from serum of a patient with macro CK-BB. Free and antibody-bound tracer were separated by anion-exchange chromatography. The affinity constant, Keq, for the binding of CK-BB to immunoglobulin was calculated as 1.4 X 10(11) L/mol, which suggests that the immunoglobulin was an autoantibody. The assay may detect 1 microgram of enzyme per liter in a 100- microL sample. CK-MM and CK-MB isoenzymes did not cross react in the assay. Within-assay precision (CV) was 5%; between-assay precision was 14 and 15% at 6 and 14 microgram of CK-BB per liter, respectively. Of 45 sera from blood donors, 95% contained &lt; 1.8 microgram of CK-BB per liter, whereas of 19 sera from unselected patients the corresponding figure was 2.8 microgram/L.
An instrument for digital matrix photometry.
Authors: Neeley W E , Epstein D , Zettner A 
Published: January 2020

Abstract
A new instrument was conceived and designed for quantitative measurement of chromophoric areas or colored spots such as are produced in (e.g.) thin-layer chromatography. The areas to be measured are subdivided grid-like into small subunits, and the absorbance of each of these is measured. The sum of absorbances for all subunits is directly proportional to the total amount of light-absorbing substances in a spot. The absorbances of the subunits are measured with a photodetector that contains hundreds of microscopically small photodiodes, arranged in a precise geometric array. The photodiode array is interfaced with a computer via an analog-to-digital converter for numerically integrating the individual signals from each photodiode. With this analytical system, quantitation of light-absorbing substance is accurate and precise for areas of different sizes, shapes, and internal irregularity.
Liquid-chromatographic assay of angiotensin-converting enzyme in serum.
Authors: Shihabi Z K , Scaro J 
Published: January 2020

Abstract
This assay of angiotensin-converting enzyme is based on release of hippuric acid from a synthetic tripeptide, hippuryl-L-histidyl-L-leucine. Hippuric acid is separated and quantitated on a reversed-phase column under conditions similar to those used for assay of theophylline and acetaminophen. The method is rapid and free from interferences.
Influence of hemolysis on the serum lactate dehydrogenase-1/lactate dehydrogenase-2 ratio as determined by an accurate thin-layer agarose electrophoresis procedure.
Authors: Leung F Y , Henderson A R 
Published: January 2020

Abstract
The accuracy of our lactate dehydrogenase (EC 1.1.1.27) isoenzyme procedure, based on electrophoresis in thin-layer agarose, has previously been assessed (Clin. Chem. 22: 1995, 1976). We now show that the method is similarly accurate and precise for the specific measurements of lactate dehydrogenase isoenzyme-1 and -2. We have also determined the lactate dehydrogenase isoenzyme pattern in peripheral erythrocytes and have found that lactate dehydrogenase-1 is usually the isoenzyme present in greatest concentration. Therefore, hemolysis may increase lactate dehydrogenase-1 in serum, affecting the lactate dehydrogenase isoenzyme ratio used in the diagnosis of myocardial infarction. This conjecture has been confirmed by in vitro experiments, and in a small group of patients with intra-vascular hemolysis.
Enzyme immunoassay for thyroxine and triiodothyronine in human serum, with use of a covalent chromatographic separation method.
Authors: Yamamoto R , Hattori S , Inukai T , Matsuura A , Yamashita K , Kosaka A , Kato K 
Published: January 2020

Abstract
A practicable enzyme immunoassay for measurement of thyroxine and triiodothyronine in serum was developed, involving a separation method based on the thiol-disulfide interchange reaction. Serum samples at alkaline pH were incubated for 1 h with antibodies and antigens labeled with beta-D-galactosidase. Each reaction mixture was then passed through a 0.1-mL column containing (anti-IgG) antibody immobilized on Sepharose 4B, to which the anti-IgG antibodies were coupled by means of a disulfide bond (3 g of IgG fraction per liter). The column was washed and the bound form of the label then was eluted from the column with a buffer containing dithiothreitol (25 mmol/L) by splitting the disulfide bonds between the anti-IgG antibody molecules and Sepharose matrix. From the enzyme activity in the eluate, concentrations of thyroxine or triiodothyronine in serum could be determined. Values obtained by this method and those obtained by a radioimmunoassay correlated well (thyroxine, r = 0.97, slope = 1.1 y-intercept = -0.94 microgram/L, n = 70; triiodothyronine, r = 0.98, slope = 0.91, y-intercept = 0.067 microgram/L, n = 77.
Use of N-methyl-D-glucamine as buffer in the determination of serum alkaline phosphatase activity.
Authors: Chromý V , Zahradnícek L , Voznícek J 
Published: January 2020

Abstract
We describe a method for determining serum alkaline phosphatase activity with use of N-methyl-D-glucamine buffer, Na+ is a definite activator, whereas NH4+ and Li+ inhibit enzyme activity. Optimum reaction conditions are: methylglucamine buffer, 0.35 mol/L, pH 10.2 +/- 0.1 (30 degrees C); NaCl, 70 mmol/L; MgCl2, 0.5 mmol/L; disodium 4-nitrophenyl phosphate, 15 mmol/L; reaction temperature, 30 degrees C; reaction time, 2 min. The assay conditions are optimum for all human serum isoenzymes.
Total-calcium measurement in serum from neonates: limitations of current methods.
Authors: Brett E M , Hicks J M 
Published: January 2020

Abstract
In the routine analysis for calcium in serum from neonates we noted large discrepancies in icteric samples analyzed by several different methods. The present investigation was undertaken to demonstrate the magnitude of the problem of bilirubin interference in calcium analysis and to assess the specific applicability of commonly used micro-methods in the pediatric or neonatal laboratory. The intention is not to advocate any single methodology but rather to point out inadequacies that must be considered. Colorimetric and fluorometric methods correlated poorly with an atomic absorption spectroscopic method for samples from pediatric patients. In addition, we noted significant interference proportional to the concentration of bilirubin. A fluorescence titration method was shown to be unacceptable for pediatric use because of the variable and unpredictable response to bilirubin interference. The study emphasizes the need for thorough invesigation of methods before they are put to use in the specialized pediatric setting.
Plasma lipid-bound sialic acid and carcinoembryonic antigen in cancer patients.
Authors: Dnistrian A M , Schwartz M K 
Published: January 2020

Abstract
We evaluated lipid-bound sialic acid as a "marker" in cancer patients and assessed the individual and combined value of lipid-bound sialic acid and carcinoembryonic antigen determinations in these patients. Plasma was sampled from 62 normal subjects and 125 cancer patients. Lipid-bound sialic acid was determined by the resorcinol method after total lipid extraction and isolation of the sialolipid fraction from plasma. Neither marker was increased in many breast cancer patients. Carcinoembryonic antigen was increased more commonly and to a greater degree in colon cancer patients and seems to be the preferred marker. Both markers were increased in lung cancer patients and their combined evaluation improved the rate of detection. Lipid-bound sialic acid was increased in more patients with leukemias, lymphomas, Hodgkin's disease, and melanomas, suggesting that it may be a useful biochemical marker in these types of cancer.
Comparison of countercurrent immunoelectrophoretic assay with commercial radioimmunoassay kits for measuring prostatic acid phosphatase.
Authors: Wright G L , Schellhammer P F , Brassil D N , Sieg S M , Leffell M S 
Published: January 2020

Abstract
We evaluated and compared five commercial radioimmunoassay kits with a standard counter-immunoelectrophoretic assay for the measurement of prostatic acid phosphatase in serum. Four of the five radioimmunoassays performed as described by the supplier with respect to sensitivity, stability, precision, linearity, analytical recovery, and expected values for the normal male population. None of the radioimmunoassays was more clinically sensitive then the counter-immunoelectrophoretic assay for detecting increased prostatic acid phosphatase in serum. Results obtained by counter-immunoelectrophoretic assay agreed with results obtained by radioimmunoassay in 96% of the tests. The proportion of positive results in patients with confirmed prostatic adenocarcinoma increased with disease progression. The fewer positive tests in localized adenocarcinoma (Stages A and B) suggests that neither the counter-immunoelectrophoretic assay nor the radioimmunoassay procedures are useful for screening unselected populations for adenocarcinoma of the prostate. The high percentage of normal values found in those patients clinically free of disease after treatment is encouraging and supports the use of the prostatic acid phosphatase immunoassays in prospectively monitoring the treatment of prostatic cancer patients.
Factitious hypophosphatemia related to mannitol therapy.
Authors: Donhowe J M , Freier E F , Wong E T , Steffes M W 
Published: January 2020

Abstract
We observed factitious hypophosphatemia in a patient who was receiving large amounts of intravenous mannitol. Mannitol concentrations as low as 25 mmol/L inhibited phosphorus measurement by the Dupont aca endpoint method; a kinetic method was unaffected. The mechanism of the mannitol interference was binding to molybdate in the reaction, decreasing both the rate of color development and the endpoint measurement. We conclude that the molybdate concentration in the DuPont method is suboptimal for measuring phosphorus in specimens containing mannitol.
The TYCHO system for computer analysis of two-dimensional gel electrophoresis patterns.
Authors: Anderson N L , Taylor J , Scandora A E , Coulter B P , Anderson N G 
Published: January 2020

Abstract
We describe here a computer system for the analysis of high-resolution two-dimensional gel-electrophoresis patterns, with some initial applications. The system (called TYCHO) comprises programs for image acquisition, background subtraction and smoothing, spot detection, gaussian spot modeling, and pattern matching and comparison. It is based on a conventional minicomputer, but makes extensive use of a high-speed array processor in the image-processing and -modeling steps. Used in concert with the ISO-DALT two-dimensional electrophoresis system (Anal. Biochem. 85:331-354, 1978), TYCHO allows quantitative measurement of hundreds of proteins in complex biological samples, and constitutes the initial data-reduction system required for work towards a Human Protein Index.
Heterogeneity of corticotropin-immunoreactive compounds in human body fluids.
Authors: Schöneshöfer M , Fenner A , Molnar I 
Published: January 2020

Abstract
Using reversed-phase "high-performance" liquid chromatography and hydrophilic ion-pairing reagents, we studied the chromatographic profiles of corticotropin immunoreactivities in human plasma, cerebrospinal fluid, and urine. The chromatographic system we applied provides excellent separation of peptide molecules, with reproducibility (CV) of retention times better than 0.5%, and makes feasible the subsequent immunological quantitation of eluted fractions. Profiles of corticotropin immunoreactivities exhibited several chemically different compounds in each of the three body fluids studied. A considerable portion of these immunoreactive compounds is more hydrophilic and probably of lower molecular mass than the human corticotropin 1-39 molecule itself. These hydrophilic molecules are more predominant in urine and plasma than in cerebrospinal fluid.
Improved radioimmunoassay for creatine kinase isoenzymes in plasma.
Authors: Ritter C S , Mumm S R , Roberts R 
Published: January 2020

Abstract
We describe convenient and relatively rapid procedures for purifying creatine kinase isoenzymes MM, BB, and MB, and their use in an improved radioimmunoassay for creatine kinase isoenzymes in plasma. The modifications include use of: (a) BB with a specific activity of 400 kU/g, which can be labeled with a specific radioactivity of 20 Ci/g; (b) albumin-free purified MB as inhibitor; (c) antiserum to MB creatine kinase; and (d) a second-antibody technique that necessitates only a 15-min incubation. The radioimmunoassay for MB has a sensitivity of 0.2 microgram/L (80 mU/L) and a CV of less than 5%. Plasma MB average 22 (SD 12) microgram/L in 200 normal subjects; 24 (SD 12) microgram/L in 200 patients with chest pain without infarction; and 23 (SD 7) microgram/L in 43 patients with renal disease, whether measured before or after dialysis. Peak values for plasma MB averaged 191 (SD 86) microgram/L in 325 patients with documented myocardial infarction; BB was negligible. Extensive clinical experience indicates the radioimmunoassay to be suitably rapid, highly sensitive, and reliable as a diagnostic assay for MB in plasma.
Reversed-phase liquid chromatography and gas chromatography/mass fragmentography compared for determination of tricyclic antidepressant drugs.
Authors: Breutzmann D A , Bowers L D 
Published: January 2020

Abstract
We compare measurement of the tricyclic antidepressants desipramine, imipramine, nortryptaline, and amitryptaline by reversed-phase "high-performance" liquid chromatography and by gas chromatography/mass fragmentography. The liquid-chromatographic procedure does not require ion-pairing reagents, and involves detection at 215 nm. The within-day and between-day CVs for this method were less than 5% and less than 7%, respectively, and linear-regression analysis of peak height vs concentration for each of the drugs showed excellent correlation (r greater than 0.97) over the range 0-250 microgram/L. Potential interferences with the internal standard (N-desmethyldoxepin) and nortryptaline were oxazepam and N-desmethyldiazepam, respectively, as shown by mass spectrometry. The interference could be circumvented by increasing the column temperature to 50 degrees C. We conclude that reversed-phase liquid chromatography with detection in the far-ultraviolet wavelengths provides an alternative to gas-chromatographic procedures for the tricyclic antidepressants, provided the analyst has prior knowledge of the patient's other medications.
16 Alpha-[125I]-beta-estradiol compared with [3H]-beta-estradiol as the tracer in estradiol receptor assays.
Authors: Tercero J C , Nelson J C , Chi E , Broughton A 
Published: January 2020

Abstract
We assessed the potential usefulness of 16 alpha-[125I]-beta-estradiol in estradiol receptor assays as compared with a long-used [3H]-beta-estradiol dextran-coated charcoal method, measuring 472 consecutive human breast-cancer cytosols by both procedures. Six different preparations of 16 alpha-[125I]-beta-estradiol were used. Nonspecific binding in five batches was similar and comparable to [3H]-beta-estradiol. Although the sixth batch had increased nonspecific binding, this did not affect results. Dissociation constants were virtually identical (r = 0.94). Results were concordant for 98.5% of cytosols: 161 were negative and 304 positive by both methods and seven were positive by one method, negative by the other. Four were positive with the 125I procedure and undetectable with [3H]-beta-estradiol. Three were measurable by both methods, but were above the cut-off value in one and below it in the other. We find 16 alpha-[125I]-beta-estradiol to be an adequate substitute for [3H]-beta-estradiol in estradiol receptor assays.
Muscle protein analysis. III. Analysis of solubilized frozen-tissue sections by two-dimensional electrophoresis.
Authors: Giometti C S , Anderson N G 
Published: January 2020

Abstract
Proteins from frozen histological sections of human muscle were analyzed by two-dimensional gel electrophoresis. Patterns so obtained were identical to those from whole homogenates of muscle prepared from frozen tissue powders that had much higher protein concentrations. To increase the number of proteins visible on gels of samples low in protein content, the gels were silver stained, or the proteins were labeled with [14C]iodoacetamide before electrophoresis and the gels were fluorographed. The latter method allow use of a single frozen-tissue section for two-dimensional electrophoretic analysis and brings the technique closer to practicable clinical use.