bluuebunny/crossref_metadata_2025_split huggingface dataset:
Serum calcium fractions in diabetes mellitus.
Authors: Fogh-Andersen N , McNair P , Møller-Petersen J , Madsbad S 
Published: January 2020

Abstract
Diabetes mellitus is associated with a decrease in bone mineral content and increased urinary excretion of calcium and phosphate. The purpose here was to elucidate the pathogenesis of these changes by comparing serum calcium fractions of diabetics and healthy controls. In a cross-sectional study, serum ionized calcium at pH 7.40, [Ca2+]7.4, of 46 insulin-treated diabetics was decreased in comparison with 44 healthy controls: mean 1.16 (SD 0.04) vs 1.21 (SD 0.03) mmol/L (p less than 0.001). The decreased [Ca2+]7.4 was associated with a higher concentration of complexed calcium in diabetic serum. The diabetics had higher concentrations of undetermined anions (p less tha 0.001) and this anion gap correlated negatively with [Ca2+]7.4 (r = -0.43, p less than 0.02). Serum [Mg2+] was decreased in the diabetics (p less than 0.001). Values for venous acid-base status, serum creatinine, total and ultrafiltrable calcium, parathyrin, and inorganic phosphate were the same in the two groups. [Ca2+]7.4, but not serum total calcium, had increased by 0.04 mmol/L (p less than 0.001) in the diabetics and by 0.02 mmol/L (p less than 0.01) in the controls by 90 min after breakfast, with and without subcutaneous insulin, respectively.
Four methods for determining uric acid compared with a candidate reference method.
Authors: Elin R J , Johnson E , Chesler R 
Published: January 2020

Abstract
Uric acid as measured in serum by three different uricase (EC 1.7.3.3) methods (aca, Ektachem, and SMAC) and by the SMAC method with phosphotungstic acid was compared with a candidate Reference Method for uric acid. Serum specimens from 83 patients (uric acid concentrations, 19 to 141 mg/L) were analyzed by all five methods. Results were compared by using linear regression analysis, and the mean difference between results by the candidate Reference Method and the four other methods was calculated. Compared with the candidate Reference Method, the aca method gave the smallest deviation from zero for the intercept and the smallest mean difference, and the SMAC phosphotungstic acid method showed a slope closest to unity. The SMAC uricase method had the largest intercept and greatest deviation of the slope from unity.
Total calcium and magnesium determined in serum with an automated stopped-flow analyzer.
Authors: Koupparis M A , Diamandis E P , Malmstadt H V 
Published: January 2020

Abstract
We describe the measurement of total calcium and magnesium in serum with an automated microcomputer-controlled stopped-flow analyzer. The calcium method is based on the cresolphthalein complexone procedure, with 2-amino-3-methyl-1-propanol as the alkalinizing agent. The assay, performed on 60-fold prediluted samples, requires 50 microL of serum. Absorbance is measured at 580 nm for 1 s, after a 5-s delay. Response is linearly related to concentration up to 5 mmol/L; analytical recovery averaged 97.8%. Within-day CVs were 0.7 to 1.5%, day-to-day CVs 1.8 to 2.5%. Results compared well with those by continuous-flow Technicon SMA II method. A sample throughput of as many as 260 samples per hour is possible. The magnesium determination, a complexometric procedure, involves magnesium/calmagite complex in an alkaline reagent mixture and ethylene glycol bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid to eliminate calcium interference. Prediluted serum samples are used (100 microL of serum diluted 25-fold), and absorbance at 520 nm is linear with concentration to 50 mg/L. Within-run CVs were 0.5 to 1.1%, and day-to-day 1.3 to 3.8%; analytical recovery was 99.3%. Results compared well with those by atomic absorption spectrometry (r = 0.994). A delay time of 10 and a measurement time of 2.5 s allows for a throughput of as many as 180 samples per hour.
Liquid-chromatographic determination of amoxapine and 8-hydroxyamoxapine in human serum.
Authors: Tasset J J , Hassan F M 
Published: January 2020

Abstract
We describe a liquid-chromatographic procedure for amoxapine and 8-hydroxyamoxapine, its active metabolite, in serum. We used a mu-Bondapak C18 reversed-phase column and a mobile phase of acetonitrile/water (74/26 by vol) plus 26 microL of n-butylamine per liter. The compounds were measured at 254 nm, with 8-methoxyloxapine as internal standard. Necessary pre-analysis purification consisted of adsorbing the drug from serum onto extraction columns, eluting with 1-butanol/hexane (1/5 by vol), re-extracting into aqueous acid, and from that re-extracting again into the elution-solvent mixture. We prefer this procedure for monitoring both therapeutic and toxic concentrations of amoxapine, because parent drug and metabolite are measured separately.
Liquid-chromatographic determination of cyclosporine in serum with use of a rapid extraction procedure.
Authors: Yee G C , Gmur D J , Kennedy M S 
Published: January 2020

Abstract
In this procedure, reversed-phase liquid chromatography is used to measure cyclosporine, a fungal metabolite with immunosuppressive activity, in human serum. With a gradient elution, the retention times for cyclosporine and cyclosporin D were 14.1 and 15.7 min, respectively. Ultraviolet absorbance at 215 nm was used to detect cyclosporine; this wavelength improved assay accuracy without decreasing sensitivity, as compared with detection at 205 nm, which is near the absorption maximum. The major advantage of our procedure is the clean-up method, which involves use of disposable extraction columns. This extraction is simple and requires only 10 to 15 min per sample. Results by radioimmunoassay for cyclosporine were unpredictably greater than those measured by the present method. Dosing guidelines for cyclosporine need re-evaluation, based on more specific assay methods.
An improved ultrafiltration method for determining free testosterone in serum.
Authors: Vlahos I , MacMahon W , Sgoutas D , Bowers W , Thompson J , Trawick W 
Published: January 2020

Abstract
In this method, we use the Amicon MPS-1 centrifugal ultrafiltration device and the YMB membrane in measuring free testosterone in serum. Two independent assays are combined: total testosterone and the ultrafiltrable fraction of added [3H]testosterone. The unbound fraction is determined in 0.15-0.5 mL ultrafiltrates of 0.6 to 1 mL of variably diluted serum that has been equilibrated with [3H]testosterone at 37 degrees C. The assay is rapid (less than 1 h), practicable (requires 0.6 mL of serum), and reproducible (CV 3.2% within assay, 3.9% between assays). Accuracy was evaluated as the fraction of free testosterone in the ultrafiltrate of dialyzed serum vs that in a prior dialysate; they were the same confirming the validity of the free testosterone measurement. Samples from ostensibly healthy men and women and from hirsute and pregnant women gave results that agreed with those obtained by equilibrium dialysis. Total testosterone concentrations for normal and hirsute women showed considerable overlap, but data on free testosterone concentrations in these populations were better resolved.
The Kodak Ektachem clinical chemistry slide for measurement of bilirubin in newborns: principles and performance.
Authors: Wu T W , Dappen G M , Powers D M , Lo D H , Rand R N , Spayd R W 
Published: January 2020

Abstract
In this slide, unconjugated bilirubin and its sugar conjugates interact with a cationic polymeric mordant to form spectrally enhanced complexes having similar absorptivities at approximately 400 nm. With reflection densitometry and appropriate mathematical transformation, readings at this wavelength are linearly related to bilirubin concentrations up to 260 mg/L. The slide requires 10 microL of serum, is precise (total CV less than 2% determined over 20 days for the analyte range 39-184 mg/L), gives results that correlate well with the Doumas et al. modification of the Jendrassik-Gróf method (slope 0.95, intercept 0.3, Sy . x 3.4, r = 0.991), and is relatively interference free. Also, the slide measures less loss of bilirubin after in vitro illumination of serum specimens than do diazo tests. An intermediate layer in the slide minimizes the spectral interference from hemoglobin and prevents the detection of the strongly protein-linked ("delta") bilirubin found in many jaundiced adults. The method is recommended for newborns (less than or equal to 14 days), in whom the incidence of delta bilirubin is negligible.
Radioimmunoassay for prostatic acid phosphatase helps discriminate patients with prostatic cancer.
Authors: Blick K E , Dick T T , Webb T A 
Published: January 2020

Abstract
We measured serum prostatic acid phosphatase in ostensibly normal controls and a selected patient population, using both a modified radioimmunoassay and an enzymic method with thymolphthalein monophosphate as substrate. The upper limit of normal for the radioimmunoassay was 2.2 micrograms/L; its sensitivity and specificity for prostatic cancer were 71 and 95%, respectively, vs 51 and 99% for the enzymic method. For both methods the correlation between clinical staging and values for acid phosphatase was poor. Our data suggest that adjunctive use of the radioimmunoassay may help further discriminate those patients requiring needle biopsy.
Mixture analysis by triple-quadrupole mass spectrometry: metabolic profiling of urinary carboxylic acids.
Authors: Hunt D F , Giordani A B , Rhodes G , Herold D A 
Published: January 2020

Abstract
In this new method for profiling urinary carboxylic acids, lyophilized urine samples are analyzed directly with a triple-quadrupole mass spectrometer. Extraction, derivatization, and lengthy gas-chromatographic separation procedures are obviated by this approach. Total sample-preparation, instrument, and data-analysis time per sample is about 15 min. More than 100 different organic acids can be detected in a typical urine sample. All components of the solid urine residue are volatilized into the ion source of the mass spectrometer and converted to (M-1)- ions by reaction with OH- under chemical ionization conditions. Quadrupole 1 is set to transmit ions of a particular m/z ratio, which in turn collide with molecular nitrogen in quadrupole 2 and dissociate to smaller charged fragments. Carboxylic acid (M-1)- ions uniquely lose either CO2 (44 atomic mass units) or both H2O and CO2 (62 atomic mass units). Quadrupole 3 is set to pass only ions that have lost either 44 or 62 atomic mass units. Accordingly, the instrument specifically detects carboxylic acids in the urine matrix and no other components. Direct analysis of polyethylene glycols and their acidic metabolites in urine and serum of a burn patient treated with an antimicrobial cream having a polyethylene glycol base is also discribed.
L-Phenylalanine inhibition of human alkaline phosphatases with p-nitrophenyl phosphate as substrate.
Authors: Komoda T , Hokari S , Sonoda M , Sakagishi Y , Tamura T 
Published: January 2020

Abstract
With p-nitrophenyl phosphate as the substrate, there reportedly is no organ-specific inhibition of alkaline phosphatase (EC 3.1.3.1) activity by L-phenylalanine. However, we found that at pH 10.0, with p-nitrophenyl phosphate as the substrate, L-phenylalanine obviously inhibits the alkaline phosphatase isoenzyme from human placenta, whereas there is little if any inhibition of the isoenzyme from human intestine. Because of the differing effects of substrates (p-nitrophenyl phosphate and phenyl phosphate) and their enzymic products (p-nitrophenol and phenol) for L-phenylalanine action on the placental alkaline phosphatase isoenzyme, we suggest that the isoenzyme--inhibitor--substrate complex and the effect of released phosphate on L-phenylalanine inhibition of the isoenzyme activity differ from each other.
Determination of selenium concentration and glutathione peroxidase activity in plasma and erythrocytes.
Authors: Pleban P A , Munyani A , Beachum J 
Published: January 2020

Abstract
We determined selenium concentrations and activities of the selenoenzyme, glutathione peroxidase (EC 1.11.1.9), in the plasma and erythrocytes of 38 apparently healthy women. We determined selenium concentrations directly by polarized Zeeman-effect flameless atomic absorption spectroscopy. Within-run precision studies for the assays gave CVs of 5.6% for a mean erythrocyte selenium concentration of 149.9 (SD 8.3) microgram/L (n = 10) and 6.4% for a mean plasma selenium concentration of 97.3 (SD 6.2) microgram/L (n = 12). For the women, mean selenium concentrations were 141.4 (SD 14.3) microgram/L of erythrocytes [0.49 (SD 0.07) microgram/g of hemoglobin and 96.3 (SD 14.2) microgram/L of plasma. Glutathione peroxidase activities were measured by a modification of the method of Paglia and Valentine (J. Lab. Clin. Med. 70: 158--169, 1967). Within-run precision studies for the glutathione peroxidase assays gave CVs of 12.8% for mean erythrocyte glutathione peroxidase activity of 77.2 (SD 9.9) U/g of hemoglobin (n = 13), and 8.1% for mean plasma activity of 312.5 (SD 25.2) U/L (n = 11). Mean enzyme activity was 78.7 (SD 12.9) U/g of hemoglobin for erythrocytes and 424 (SD 40) U/L for plasma. Erythrocyte selenium concentrations and glutathione peroxidase activities were positively, but poorly, correlated (r = 0.41, p less than 0.01).
FLow-injection analysis: a new approach to quantitative measurements in clinical chemistry.
Authors: Rocks B , Riley C 
Published: January 2020

Abstract
Flow-injection analysis, founded on an approach that is entirely different from continuous-flow analysis, involves use of three principles: sample "injection," controlled dispersion of sample (rather than a dispersion retarded with gas bubbles), and reproducible timing. The conditions governing the dispersion of the sample in the flowing carrier stream are considered, and we illustrate how the dispersion can be manipulated to suit particular analytical requirements. Instrumentation and practical aspects of flow-injection analyses are discussed, especially with regard to clinical chemistry applications, and the technique is compared with the more conventional gas-segmented-flow analysis system. We conclude that, because of its speed, economy, and simplicity, flow-injection analysis will eventually replace the gas-segmented approach for many clinical chemistry analyses.
Enzyme immunoassay for tartrate-resistant acid phosphatase.
Authors: Lam K W , Siemens M , Sun T , Li C Y , Yam L T 
Published: January 2020

Abstract
An immunochemical method for quantitative analysis of the tartrate-resistant acid phosphatase (EC 3.1.3.2), band 5, is presented. This method involves precipitation of the enzyme from the serum by the antibody specific to band 5 and by sheep anti-rabbit immunoglobulin, followed by analysis of the enzyme activity in the precipitate. The precipitation procedure eliminates the interferences of the tartrate-sensitive phosphatase of all tissues, of the tartrate-resistant phosphatase of erythrocytes, and of unknown substances that interfere with the colorimetric method. We compare the present method with previously described colorimetric and electrophoretic methods.
Rapid quantitation of serum immunoglobulins with a miniature centrifugal analyzer.
Authors: Koch T R , Adolf P K , Zimmerman D H , Knoblock E C , Leitz V M 
Published: January 2020

Abstract
For these quantitative turbidimetric assays for immunoglobulins IgG, IgA, and IgM in serum, the reagents used are commercially available in kit form. The two-point assays are performed with a miniature centrifugal analyzer (GEMENI, Electro-Nucleonics, Inc.). The reading taken 5 s after mixing is used to correct for specimen turbidity. Run-to-run precision (CV) was typically 5% (range: 3.0-8.7%). Excellent correlation with radial immunodiffusion was observed for each test (r greater than 0.98 for each test). The dynamic range of each test extends above and below the reference-interval ranges.
Methemoglobin in blood as determined by double-wavelength spectrophotometry.
Authors: Sakata M , Yoshida A , Haga M 
Published: January 2020

Abstract
We describe spectrophotometric determination of methemoglobin (Met-Hb) in blood by absorbance differences at two wavelengths (characteristic of the instrument used) in the 500-600 nm region. Blood is diluted 100- to 200-fold with a solution containing KCN and carbon monoxide to convert hemoglobin to carboxyhemoglobin and Met-Hb to cyanomethemoglobin (CN-Met-Hb). Carboxyhemoglobin has the same absorbance at the two wavelengths used, so that the differences in absorbance reflect only the CN-Met-Hb component. After measurement of absorbance differences, potassium ferricyanide is added to convert all hemoglobin derivatives to CN-Met-Hb; samples are then remeasured at the same wavelengths. The percentage of Met-Hb is determined from the ratio of the absorbance differences. Results agree satisfactorily with currently accepted procedures and with calculated theoretical results for mixtures of oxyhemoglobin, carboxyhemoglobin, and Met-Hb.
Measurement of magnesium by continuous-flow colorimetry.
Authors: Fowler R T , Abernethy M H , Walmsley T A , Taylor H W 
Published: January 2020

Abstract
We describe the application to the Technicon SMAC system of a micellar-improved calmagite method for the measurement of magnesium. In this continuous-flow method a dialyzer is not needed, because protein interference is negligible. Sample interaction was estimated to be 3%. The increased sensitivity of the method allows for a small sample volume (37 microL/min). Results obtained agreed well with those by an atomic absorption procedure (x): SMAC magnesium - 0.971 x + 0.030 mmol/L (n = 58). The estimated total error for the SMAC procedure was less than 50 mumol/L at two analyte concentrations: 0.50 and 1.50 mmol/L. The inclusion of magnesium estimation on SMAC should extend the screening function of this analyzer.
Two-dimensional gel electrophoresis of cell proteins in childhood leukemia, with silver staining: a preliminary report.
Authors: Hanash S M , Tubergen D G , Heyn R M , Neel J V , Sandy L , Stevens G S , Rosenblum B B , Krzesicki R F 
Published: January 2020

Abstract
We have investigated the potential of two-dimensional electrophoresis for identifying differences in protein patterns between acute lymphocytic (ALL) and acute myelogenous leukemia (AML). We studied blood cells directly isolated from seven children with non-T, non-B ALL and five with AML. Solubilized proteins were electrophoresed with the ISO-DALT system and made visible by silver staining. More than 800 spots were routinely detected in individual gels. Patterns for multiple runs of the same sample were indistinguishable. Most of the prominent spots were present in gels from all 12 of the individuals studied. However, substantial variability in spot intensity was observed, even among patients in the same group. Five spots were consistently present in gels of all the AML patient, and either completely absent or substantially decreased in ALL gels. Three other spots were present in ALL but not AML gels. We conclude that this may be a useful tool for characterizing leukemic cells.
Proteins of human milk. I. Identification of major components.
Authors: Anderson N G , Powers M T , Tollaksen S L 
Published: January 2020

Abstract
Traditionally, human milk proteins are identified largely by reference to bovine milk. Hence, to identify the major proteins in human milk, we subjected human and bovine milk, in parallel, to high-resolution two-dimensional electrophoresis. Isoelectric precipitation at pH 4.6 was our criterion for distinguishing whey proteins from those of the casein complex. The alpha- and beta-caseins were identified on the basis of relative abundance, relative molecular mass, and relative isoelectric points. Kappa casein was identified as a series of four spots, which disappear from bovine skim milk treated with rennin (chymosin; EC 3.4.23.4) during the clotting process. Para kappa-casein does not appear on the standard ISO-DALT pattern after treatment of bovine milk with rennin, but does appear in BASO-DALT pattern, indicating its high isoelectric point. No protein disappeared from ISO-DALT patterns of human milk after rennin treatment, and no new protein comparable to bovine para kappa-casein appeared in the BASO-DALT patterns; this suggests that kappa-casein is absent from human milk. The proteins identified in human milk patterns include the alpha and beta casein families, lactalbumin, albumin, transferrin, IgA, and lactoferrin. Numerous additional proteins seen in patterns for human milk remain to be identified.
Hair as an indicator of excessive aluminum exposure.
Authors: Yokel R A 
Published: January 2020

Abstract
To determine if excessive systemic exposure to aluminum would be reflected in increased aluminum concentration in hair, rabbits were given a series of aluminum lactate injections. Hair was collected before the aluminum lactate administration from the site of injections and twice after the injections from this site as well as from an area adjoining the injection site. Aluminum was determined by flameless atomic absorption analysis of acid-digested samples. The concentration of aluminum in the hair increased after the injections in samples taken at both times from both sites. Considerable variability in hair aluminum was found before excessive exposure, as has been reported in humans, and in response to the exposure. The increase in hair aluminum did not correlate with the amount of hair produced. Nevertheless, because some subjects exposed to excessive aluminum showed a very large increase in hair aluminum, hair may be a useful indicator of aluminum body burden in such aluminum-induced conditions as dialysis encephalopathy.
Standardization of serum cholesterol assays by use of serum calibrators and direct addition of Liebermann-Burchard reagent.
Authors: Katan M B , van der Haar F , Kromhout D , Schouten F J 
Published: January 2020

Abstract
Serum cholesterol concentrations of subjects in epidemiological studies were measured after direct addition of Liebermann-Burchard reagent; results were calibrated with human serum pools assayed according to Abell et al. (J. Biol. Chem. 195:357-366, 1952). Accuracy and precision were monitored for six years by analysis of internal-control pools and blind external-control pools. For various internal-control pools, the imprecision (CV) of the long-term averages of run means ranged from 0.5 to 0.9%. The within-run CV for internal control and patients' sera was about 1%. For blind control sera with different concentrations (provided by the Centers for Disease Control, Atlanta, GA, over the same period), the average difference per three-month period between the values found and the target values was usually between -0.5% and +0.7% for medium-concentration pools and between -2% and +2% for low- and high-concentration pools (extreme values: -2.4% and +2.5%). The CV per three-month period ranged from 0.6 to 2.7%. Sera from subjects on diets of high or low linoleic acid content were analyzed to study the effect of the fatty acid portion of serum cholesterol esters; the differences between values obtained with the comparison method and the direct method was insignificant on both diets. We conclude that the use of serum calibrators eliminates the bias inherent in the direct method.
Liquid-chromatographic analysis for serum theophylline in less than 70 seconds.
Authors: Kabra P M , Marton L J 
Published: January 2020

Abstract
We describe a sensitive, specific, and very fast liquid-chromatographic assay for serum theophylline, involving a commercially available high-speed reversed-phase column and a micro-flow-cell-equipped detector. Each analysis requires only 100 microL of serum (as little as 25 microL may be used when necessary), and chromatography is complete in less than 70 s. Analytical recovery of theophylline added to serum ranged from 97 to 102%. Between-run precision (CV) ranged from 2.1 to 3.5%. The lower limit of detection for theophylline is 0.5 mg/L, and linearity extends to 50 mg/L. Numerous drugs and xanthine metabolites tested do not interfere.