bluuebunny/crossref_metadata_2025_split huggingface dataset:
Quantitative determination of lecithin and sphingomyelin in amniotic fluid.
Authors: Yee H Y 
Published: January 2020

Abstract
A quantitative method for lecithin and sphingomyelin is presented. In this method, which may be calibrated with a primary standard phosphate salt or pure phospholipids, 2 mL of amniotic fluid is extracted, and the solvent passed through a column of hydroxyapatite to remove all phospholipids except lecithin and sphingomyelin. After evaporation, the residue is treated with methanolic sodium hydroxide, which hydrolyzes lecithin to inorganic phosphate and a methyl ester. The unreacted sphingomyelin is removed by extraction, and the solvent evaporated. Both fractions are digested and assayed for phosphate by reduced phosphomolybdate. The total time required is 2 h. Analytical recoveries were 91-97%, and excellent agreement was found for controls. Amniotic fluid specimens were assayed to illustrate application of the proposed method. If this method is used for obtaining a lecithin/sphingomyelin ratio, a new ranges must be established, as this method is not equivalent to thin-layer chromatographic ones.
Two automated methods for plasma antithrombin III compared, and the clinical significance of the results.
Authors: Prellwitz W , Schmitt K F , Machner M , Schuster C J , Weilemann L 
Published: January 2020

Abstract
Antithrombin III (AT III) activity was determined with two different new chromogenic substances--Chromozym-TH (Tos-Gly-Arg-p-nitroanilide; Boehringer Mannheim) and alpha-N-carbobenzyl-oxy-L-lysine-thiobenzyl ester (Du Pont)--with both a discrete (aca) and a centrifugal analyzer (COBAS BIO). The correlation between the Chromozym-TH/centrifugal analyzer and Du Pont ester/aca methods was good (r = 0.9890). Precision within and between runs was similar to that for typical enzymic determinations. AT III in plasma of 226 healthy men and women ranged from 76.6 to 141.1% (100% = "normal"). We found no significant differences ascribable to oral contraceptives. AT III activity was decreased in 27% of patients with acute thromboembolic diseases (n = 62), in 48% of patients the first day after abdominal operations without complications (n = 78), and in 100% of patients with reversible or irreversible shock (n = 58). In patients receiving continuous therapy with heparin (1500 USP units/h) we saw no decrease in AT III within 96 h of beginning treatment. Plasma from 14 of 16 patients with disseminated intravascular coagulopathy showed a decrease in AT III of from 17 to 51% of normal before and during heparin therapy. We then treated all 16 patients with AT III concentrate. During such treatment, AT III in plasma must be monitored over short intervals to assure that sufficiently high proportions of AT III (greater than 70% of normal) are reached.
Liquid-chromatographic procedure for simultaneous analysis for eight benzodiazepines in serum.
Authors: Lensmeyer G L , Rajani C , Evenson M A 
Published: January 2020

Abstract
We describe an efficient extraction and liquid-chromatographic method for separating commonly encountered benzodiazepine drugs and their pharmacologically active metabolites. After a single extraction of the drugs from serum, chlordiazepoxide, demoxepam, N-desmethyl-chloriazepoxide, diazepam, N-desmethyldiazepam, N-desalkylflurazepam, oxazepam, and prazepam can be resolved and quantified by using a C18 reversed-phase "high-performance" column and a ternary-solvent gradient system. Three separate solutions [60 mmol/L ammonium acetate (pH 7.69), 60 mmol/L acetic acid (pH 2.8), and acetonitrile] were incorporated into a gradient mobile phase such that changes in pH and solvent composition occur. Complete chromatographic resolution of the benzodiazepines resulted, permitting quantification of all within 15 min. The standard curve is linear to at least 8 mg/L for each drug, and the detection limit for each was 0.05-0.10 mg/L. The day-to-day precision for both high and low concentrations yielded CVs of 5 to 9%. Extraction of each drug from serum was 95 to 100% complete. Exogenous and endogenous interferences are minimal. Finally, we circumvented the instability problem of benzodiazepine standards in solution by using a simple reduced-pressure drying process that produces a working standard that is stable for at least nine months.
Urine contains an inhibitor for turbidimetric determinations of protein.
Authors: Nakamura J , Yakata M 
Published: January 2020

Abstract
Our examination of urine components separated by gel filtration revealed the presence of an inhibitor that decreases the analytical recovery of protein in a turbidimetric assay involving sulfosalicylic acid as reagent (Proc. Soc. Exp. Biol. Med. 92: 748, 1956). The apparent relative molecular mass of this inhibitor was in the range 160 000-240 000. A study with purified proteins showed a similar inhibition by gamma-globulin, glycoprotein, and beta-lipoprotein in the assay of albumin by the same turbidimetric method. In contrast, measurement of protein by a dye binding method was not affected by these materials. The low values for apparent urinary protein given by the turbidimetric method as compared with those by the dye-binding method are at least partly ascribable to the inhibitor.
High-resolution zone electrophoresis, combined with immunofixation, in the detection of an occult myeloma paraprotein.
Authors: Reichert C M , Everett D F , Nadler P I , Papadopoulos N M 
Published: January 2020

Abstract
A high-resolution agarose gel electrophoretic technique, coupled with immunofixation, was used to follow paraprotein concentrations retrospectively in a patient with multiple myeloma of nine years' duration. Although the patient's IgA lambda gammopathy "disappeared" shortly after the initiation of therapy, as judged by routine cellulose acetate electrophoresis and immunoelectrophoresis, high-resolution zone electrophoresis demonstrated a monoclonal band that we identified by immunofixation as the IgA lambda paraprotein. The combination of the two simple, inexpensive, and reliable techniques of high-resolution agarose electrophoresis and immunofixation thereby permitted detection and identification of a myeloma protein in a patient otherwise thought to be in complete remission. We believe this approach is useful in assessing persistent or recurrent disease in patients with a known history of myeloma; this combination of techniques may also prove beneficial in the early diagnosis of multiple myeloma.
Protein A-bearing Staphylococcus aureus as the solid phase in an enzyme immunoassay and its application to determination of urinary albumin.
Authors: Harper J R , Mahmoudi N , Orengo A 
Published: January 2020

Abstract
Protein A-bearing Staphylococcus aureus was used as a solid-phase matrix in a sandwich-type enzyme immunoassay for urinary albumin. Heat-inactivated, formalin-fixed bacteria were coated with affinity-purified goat anti-human albumin, exposed to solutions containing standard or unknown concentrations of albumin, then challenged with an alkaline phosphatase/anti-human albumin conjugate obtained by periodate oxidation. Alkaline phosphatase activity bound to the bacteria was a function of albumin concentration from 25 to 1000 micrograms/L. This assay was applied to determinations of urinary albumin concentrations between 1.25 and 1000 mg/L. Between-run CV was 2.55 (63.9 mg/L concentration). Within-run CVs for albumin concentrations of 1.9, 38.1, and 638.0 mg/L were 3.7, 3.7, and 2.4%, respectively. Analytical recovery was 95 to 107% across the full working range of the assay. Bence Jones proteins and hemoglobin had no significant effect on the assay. Nonspecific binding of the enzyme-antibody conjugate was 1.3% (SD = 0.7%). Values agreed well with those by radial immunodiffusion.
Anatomically-related variations in trace-metal concentrations in hair.
Authors: DeAntonio S M , Katz S A , Scheiner D M , Wood J D 
Published: January 2020

Abstract
Scalp-hair analysis is used as an indicator of trace-metal concentrations in the human body. The major shortcoming of this approach is the inability to differentiate between endogenous and exogenous trace metals. Our analyses show no correlation between the concentrations of calcium, magnesium, copper, iron, or zinc in scalp hair and pubic hair in 67 donor-matched hair samples. We interpret this as a strong indication that exogenous trace metals make a significant contribution to the results for trace metals in human hair.
Transformation of creatine kinase-BB isoenzyme in vitro: effect of carboxylic acids, thiols, pH, cations, and chelators.
Authors: Lott J A , Heinz J W 
Published: January 2020

Abstract
Creatine kinase isoenzyme BB from rat brain was incubated with serum, dialyzed serum, or plasma, with added carboxylic acids, thiols, buffers, or cations. It was found to be very unstable at 37 degrees C under all these conditions, being transformed to CK-BB', a form that migrates like CK-MB on agarose electrophoretic plates. This transformation is enhanced at alkaline pH and, especially, by Zn2+. CK-BB' is quite stable, and probably results from binding of cations to CK-BB, because the transformation is prevented by EDTA and citrate.
A more specific, liquid-chromatographic method for free cortisol in urine.
Authors: Canalis E , Reardon G E , Caldarella A M 
Published: January 2020

Abstract
Currently used assays for urinary cortisol reportedly overestimate it, owing to cross-reacting substances. We describe here a method for separating and measuring by liquid chromatography cortisol extracted from urine. The method is specific for cortisol and as little as 5 ng per sample can be measured. Mean analytical recovery of added cortisol was 98.8% (SD 6.1%) and the coefficients of variation ranged from 3.1 to 4.7% (within-day) and from 7.1 to 14% (between-day). Mean (and SD) urinary excretion of cortisol for 45 normal men and women was 20.1 (SD 7.6) micrograms/24 h; for 29 children it was 14.1 (SD 6.0) micrograms/24 h. Results by radioimmunoassay were 1.4- to 4.3-fold greater than by this method, and results of the two assays did not correlate well (r = 0.59, p less than 0.01). We consider the present method to be a practical and specific assay for three cortisol in urine.
Falsely negative laboratory diagnosis for myocardial infarction owing to the concurrent presence of macro creatine kinase and macro lactate dehydrogenase.
Authors: Pudek M R , Jacobson B E 
Published: January 2020

Abstract
Macro creatine kinase (CK, EC 2.7.3.2) and macro lactate dehydrogenase (LD, EC 1.1.1.27) were both present in the serum of a 70-year-old woman with myocardial infarction. This interfered with the interpretation of the CK and LD isoenzyme analyses. Gel filtration and immunoprecipitation showed that the macro CK consisted of IgG and CK and the macro LD of IgG and LD. The IgG in this patient bound both MB and BB isoenzymes of CK, resulting in a macro CK complex that co-migrated with CK-MM on cellulose acetate electrophoresis. This situation led to a falsely negative laboratory diagnosis for myocardial infarction.
Effectiveness of analysis of free thyroxin concentration in serum for diagnosis of covert thyroid disease.
Authors: Symons R G , Walichnowski C M , Murphy L J 
Published: January 2020

Abstract
The indirect indices of free-thyroxin concentration (fT4) are of limited effectiveness in diagnosing covert (mild) thyroid disease. We compared measurements of fT4 and of normalized T4 (NT4, the effective thyroxin ratio) in a group of patients being treated for thyroid disease, most of whom were clinically euthyroid. Although fT4 values correlated well with NT4, many of the patients (34% in one of the comparisons) had fT4 and NT4 values that gave different indications of thyroid status. A review of the patients' treatment and other biochemical indications revealed that measurements of fT4 were more effective in detecting mild disturbances of thyrometabolic status than were assays for NT4, total T4, total triiodothyronine, or thyrotropin. This study suggests that direct fT4 assays are particularly useful in diagnosing covert thyroid disease.
A candidate reference method for uric acid in serum. II. Interlaboratory testing.
Authors: Duncan P , Gochman N , Bayse D , Burnett R , Carey N , Carter R , Fellows W D , Garber C , Kessler G , McComb R , Miller W , Nast P , Ryan W , Schaffer R , Tejeda B , Vanderlinde R , Widdowson G 
Published: January 2020

Abstract
We describe the interlaboratory testing of a candidate Reference Method (Part I) for uric acid in serum. The method is based on the ultrasound spectrophotometric quantitation of uric acid before and after incubation with uricase. A comprehensive investigation involving 12 laboratories was organized to document the transferability, intra- and interlaboratory precision, and general reliability of the candidate Reference Method. The interlaboratory CV with this method was about 2 to 6% for uric acid concentrations ranging from 0.12 to 0.60 mmol/L. The results detailed here demonstrate that the method can be successfully duplicated among different laboratories.
Clinical significance of plasma galactose and erythrocyte galactose-1-phosphate measurements in transferase-deficient galactosemia and in individuals with below-normal transferase activity.
Authors: Pesce M A , Bodourian S H 
Published: January 2020

Abstract
We correlated the clinical symptoms of transferase-deficient galactosemia with the plasma galactose and erythrocyte galactose-1-phosphate concentrations in six galactosemic patients during dietary treatment, in a child before treatment, and in 12 individuals with below-normal erythrocyte hexose-1-phosphate uridylyltransferase activity. All the treated patients were asymptomatic. Normal galactose and either normal or above-normal galactose-1-phosphate concentrations were found. Three of these patients were clinically normal as newborns while ingesting galactose-containing foods and may resemble the asymptomatic Negro galactosemic. The clinical symptoms of galactosemia were observed in the untreated patient, who showed markedly above-normal concentrations of galactose and galactose-1-phosphate, protein and reducing substances in the urine, above-normal bilirubin and alkaline phosphatase in the plasma, with normal values for glucose, aspartate aminotransferase, alanine aminotransferase, and gamma-glutamyltransferase. Clinical improvement in this patient paralleled the decline in erythrocyte galactose-1-phosphate. The individuals with below-normal hexose-1-phosphate uridylyltransferase activity (range 7--17 U/g of hemoglobin) had normal galactose and galactose-1-phosphate concentrations and were asymptomatic.
Dissociation of mannan--serum complexes and detection of Candida albicans mannan by enzyme immunoassay variations.
Authors: Reiss E , Stockman L , Kuykendall R J , Smith S J 
Published: January 2020

Abstract
Candida albicans mannan was added to normal human sera and the resulting complexes were dissociated by boiling (boil) with EDTA or by alkali treatment (bead method). The mannan released was detected by "sandwich" enzyme immunoassay (EIA) or by EIA inhibition. Each EIA took 2.3 h to perform. The total time for the boil-EIA combination was 2.7 h and for the bead-EIA, 3.8 h. The temperature favorable for antigen--antibody incubation was 4 degrees C. The sandwich EIAs were preferable to EIA inhibition because absorbance was directly proportional to mannan concentration, within-run variation was decreased, and accuracy was increased. The boil-sandwich EIA had the highest sensitivity in the 12.5 to 200 micrograms/L range.
Relationships of bilirubin binding parameters.
Authors: Wells R , Hammond K , Lamola A A , Blumberg W E 
Published: January 2020

Abstract
The apparent unbound bilirubin concentration by the "peroxidase" method (U) and the total unconjugated bilirubin in blood (T), albumin-bound bilirubin (B), and reserve bilirubin binding capacity (R) by the bilirubin hematofluorometer were measured in 164 specimens from 98 neonates and in a series of artifactual specimens, made by adding bilirubin to the blood of a single adult donor. Linear correlations between U and (B/R) were found for both the prepared specimens (r = 0.99) and the clinical specimens (r = 0.87), with the slopes of the regression lines being close to the reciprocal of the albumin-bilirubin binding constant, a prediction of the mass action law. An excellent linear correlation was observed for the prepared specimens (r = 0.96) between U and (T--B), the concentration of bilirubin bound to low-affinity secondary sites ("loosely bound bilirubin"). A simple model for low-affinity binding of bilirubin in blood predicts this simple relation. A significant linear correlation between U and (T--B) was found for the clinical specimens, although the correlation was less good (r = 0.72), as one would expect. The demonstrated simple linear relationships between U, (B/R), and (T--B) support the hypothesis that both the hematofluorometer and peroxidase methods provide valid measurements of bilirubin binding status.
Sodium ion binding in human serum.
Authors: Kissel T R , Sandifer J R , Zumbulyadis N 
Published: January 2020

Abstract
The amount of sodium ion binding in human sera and in dialyzed human sera was estimated from standard-addition titrations with an ion-selective electrode and from measurements of 23Na nuclear magnetic resonance (NMR) linewidth. For the untreated sera, maximum binding was 1% (1.4 mmol/L) as indicated by NMR; virtually no binding was found via the titration method. For dialyzed sera with low-sodium, normal-protein content, NMR indicated that sodium binding was less than 1.3% (0.14 mmol/L). The same dialyzed fluid analyzed with ion-selective electrodes shows no sodium binding, within the limits of experimental error (+/- 4%). Sodium ion binding to serum protein thus contributes only minimally to differences in sodium measurements observed between the direct (undiluted) ion-selective electrode and flame-photometric methods.
Direct radioimmunoassays for "aldosterone" and "18-hydroxycorticosterone" in unprocessed urine, and their use in screening to distinguish primary aldosteronism from hypertension.
Authors: Vecsei P , Benraad T J , Hofman J , Abdelhamid S , Haack D , Lichtwald K 
Published: January 2020

Abstract
For distinguishing primary aldosteronism from essential hypertension, we use simple direct radioimmunoassays for "aldosterone" (aldosterone and other materials that react with the antibody to aldosterone) and "18-hydroxycorticosterone" (similarly) in unprocessed urine. Patients with primary aldosteronism have high values for "aldosterone." This diagnosis can be validated by assays of further urine samples from the same person and by additional direct assays for "18-hydroxycorticosterone." In none of 65 urine samples from 26 patients with primary aldosteronism were both "aldosterone" and "18-hydroxycorticosterone" values within their reference intervals. However, a few "aldosterone" and "18-hydroxycorticosterone" values for patients with essential hypertension and normal aldosterone excretion were also (moderately) increased. Thus, when high values are found, true aldosterone values must be estimated by extraction and chromatography, to eliminate false positives. The "aldosterone" and "18-hydroxycorticosterone" values by our procedure are much higher than the corresponding values for urinary free aldosterone and 18-hydroxycorticosterone. Although not identified, the immunoactive materials are probably metabolites of aldosterone and 18-hydroxycorticosterone.
Measuring hemoglobin in plasma by reaction with tetramethylbenzidine.
Authors: Levinson S S , Goldman J 
Published: January 2020

Abstract
The reaction of hemoglobin with tetramethylbenzidine was studied with a centrifugal analyzer. We found that the hemochromogen reaction was significantly influenced by albumin. Increasing amounts of albumin apparently stimulate the hemochromogen reaction during the earlier part of an incubation and inhibit it later in the incubation. However, during an intermediate period, when the crossover from stimulation to inhibition occurs, the assay is independent of albumin and bilirubin concentrations. Increasing the temperature of incubation or the hydrogen peroxide concentration, or decreasing the tetramethylbenzidine concentration, shortens the crossover time. By adjusting these variables the method can be used with most instrumentation. We developed procedures for use on a centrifugal analyzer or for manual assay (reaction times, 4 and 20 min, respectively). Accuracy, as indicated by a comparison with a direct hemoglobin method (r = 0.990) and by recovery experiments, was excellent. The CV for the automated assay was less than 3%. Plasma collected in citrate and heparin showed good recovery of hemoglobin; recovery in EDTA was poorer.
Purification of tracer for somatomedin C radioimmunoassay by hydrophobic interaction chromatography.
Authors: Baxter R C , Brown A S 
Published: January 2020

Abstract
We have purified tracer for use in the somatomedin C radioimmunoassay by hydrophobic interaction chromatography. Material showing greatest immunoreactivity binds to Octyl Sepharose CL-4B (Pharmacia) in a buffer mixture consisting of 130 mL of acetonitrile and 870 mL of 0.1 mol/L NH4HCO3, pH 7.8, but is eluted by increasing the acetonitrile content to 180 mL/L. As compared with tracer purified by binding to specific antiserum in liquid phase, precipitating the complex with second antibody, and then dissociating by gel chromatography at acid pH, this tracer shows equal immunoreactivity against specific somatomedin C antiserum. Either preparation allows excellent discrimination between extracts of normal, acromegalic, and hypopituitary plasma samples; thus either is suitable for use in the somatomedin C radioimmunoassay. Tracer purification by hydrophobic interaction chromatography is rapid and inexpensive. It may be useful in preparing highly immunoreactive tracers for other peptide radioimmunoassays.
Rapid method for eliminating labile glycosylated hemoglobin from the assay for hemoglobin A1.
Authors: Nathan D M , Avezzano E , Palmer J L 
Published: January 2020

Abstract
The irreversible formation of stable glycosylated hemoglobin proceeds through a labile intermediate that is indistinguishable, by most methods, from the stable glycosylated product. The inclusion of the labile intermediate, which changes acutely with acute blood glucose changes, detracts from the utility of the assay as an index of chronic glucose concentration. We have developed a rapid, reliable chemical method for eliminating the labile intermediate: a 30-min incubation of whole-blood samples with semi-carbazide (30 mmol/L) and aniline (12 mmol/L) at pH 5 and 38 degrees C. The semicarbazide serves as a glucose trap; the transfer of glucose from the labile glycosylated hemoglobin to the semicarbazide is catalyzed by the acidic pH and aniline. This treatment is effective in the three most commonly used assays: "high-performance" liquid chromatography, electrophoresis, and a minicolumn kit.