bluuebunny/crossref_metadata_2025_split huggingface dataset:
"ULtra-clean" isotope diultion/mass spectrometic analyses for lead in human blood plasma indicated that most reported values are artificially high.
Authors: Everson J , Patterson C C 
Published: January 2020

Abstract
We measured lead concentrations in venous blood plasma from two subjects, one having a typical exposure and the other a high exposure to lead. Our preliminary data, obtained by isotope dilution/mass spectrometric techniques in an ultra-clean laboratory, show lead concentrations of 0.02 mug/L and 2 mug/L, respectively, in their blood plasma, and 110 mug/L and 800 mug/L, respectively, in samples of whole blood. These results indicate that plasma lead concentrations previously reported have been overestimated by a large factor, and that further improvements in analytical procedures are needed in most laboratories before data on lead concentratios in blood plasma can be properly interpreted. Our preliminary data indicate a positive correlation between lead intake and lead concentrations in blood plasma.
Detection of alkaline phosphatase/immunoglobulin complexes.
Authors: Buttery J E , Milner C R , Nenadovic P , Pannall P R 
Published: January 2020

Abstract
We report another patient with a circulating alkaline phosphatase/immunoglobulin complex in his blood, and describe a simple method of demonstrating such complexes. On electrophoresis on cellulose acetate, the complex was relatively slow moving and there was no activity in the normal bone/liver isoenzyme region. When the serum was treated with trypsin, the slow band disappeared and the normal pattern was restored.
Single- and coupled-enzyme nylon-tube reactors for plasma glucose determination with glucose oxidase and aldehyde dehydrogenase.
Authors: Hinsch W , Antonijewić A , Sundaram P V 
Published: January 2020

Abstract
We describe routine methods for determining glucose in plasma with use of aldehyde dehydrogenase or glucose oxidase-aldehyde dehydrogenase immobilized in a nylon tube that is integrated into a continuous-flow system. Although the coupled-enzyme nylon-tube reactors require the presence of a third enzyme, catalase, in solution, the kinetics are not so complicated as to preclude reliable routine determination of glucose at very low cost. Precision is good, and results correlate well with those by the method involving glucose oxidase in solution. More than 3000 tests may be carried out with one reactor. The immobilized enzymes are stable for several months at 4 degrees C when not in use.
Reactivity of amniotic fluid alpha-fetoprotein with concanavalin A in relation to gestational age: clinical implications.
Authors: Toftager-Larsen K , Kjaersgaard E , Jacobsen J C , Nørgaard-Pedersen B 
Published: January 2020

Abstract
We used concanavalin A crossed-line affinity immunoelectrophoresis to determine the percentage of concanavalin A nonreactive alpha-fetoprotein in amniotic fluid samples from pregnancies with normal and abnormal fetuses. In 167 samples from pregnancies with a normal outcome and normal values for total alpha-fetoprotein concentration in amniotic fluid the percentage decreased from a median value of 27.4% in the 13th week to 8.5% in the 21st week of gestation, and a statistically significant (p &lt; 0.001) average decrease of 1.7% per week was found from the 14th to the 19th week. A similar average decrease (2.2%) was found in 22 pregnancies from which two or more samples were obtained. The clinical significance of this decrease is discussed. Of 108 samples from patients with above-normal values for total alpha-fetoprotein and a normal outcome, seven had a total alpha-fetoprotein above recommended cut-off values, and only one of these had a low percentage of concanavalin A nonreactive alpha-fetoprotein. In contrast, for all 27 samples from pregnancies with a severe fetal malformation this percentage was low, even in one case where the total alpha-fetoprotein concentration was below the recommended cut-off value.
C-terminal parathyrin (parathyroid hormone) radioimmunoassay in serum with commercially available reagents.
Authors: Simon M , Cuan J 
Published: January 2020

Abstract
We describe a sequential double-antibody assay for measuring C-terminal parathyrin in serum with commercially available reagents. Intact bovine hormone, used as a working standard, is iodinated by conventional Chloramine T procedures. The antibody affinity is characteristic of high affinity binding (1.4 to 1.6 x 10(10) L/mol of intact parathyrin). The antibody also cross reacts with a C-terminal parathyrin fragment (amino acids 53-84) but not with a synthetic N-terminal parathyrin fragment (amino acids 1-34). The assay thus also measures both a C-terminal fragment of parathyrin and the intact hormone. The detection limit (250 ng/L; 500 int. units/L) is below the reference interval for healthy adults (430-1860 ng/L; 860-3720 int. units/L). Several commonly recognized problems with iodinated parathyrin are eliminated and accuracy and precision of the procedures for standard preparation and calibration are improved. Overall CV (between-run imprecision) is 10-17%. Analytical recovery is 80-90%, and C-terminal parathyrin measured in fresh sera and in sera stored for seven days at 30 degrees C is equivalent.
Magnetizable solid-phase fluoroimmunoassay of thyroxine by a sequential addition technique.
Authors: Nargessi R D , Ackland J , Hassan M , Forrest G C , Smith D S , Landon J 
Published: January 2020

Abstract
We describe a simple fluoroimmunoassay for the determination of thyroxine concentrations in serum. The method, "sequential addition, separation fluoroimmunoassay," involves both thyroxine labeled with fluorescein and magnetizable cellulose/iron oxide particles to which antibodies to thyroxine have been covalently linked. Serum sample or standard is incubated with an excess of the solid-phase antibody; the particles, which now carry most of the antigen in the sample, are sedimented onto a magnet and the supernate, which contains endogenous fluorophores and other interfering factors, is removed and discarded. Excess labeled thyroxine is then added, and, after incubation, the fluorescence in the supernate (free fraction), which is related directly to the amount of thyroxine in the sample is measured. For the whole procedure, including fluorometry, each sample is treated entirely within disposable polystyrene test tubes. Correlation studies with two different radioimmunoassays showed good agreement.
Study of an enzyme immunoassay kit for carcinoembryonic antigen.
Authors: Maiolini R , Bagrel A , Chavance C , Krebs B , Herbeth B , Masseyeff R 
Published: January 2020

Abstract
We evaluated a commercial enzyme immunoassay kit for carcinoembryonic antigen (CEA) based on a non-competitive "sandwich principle" method (Abbott Laboratories). The serum sample is treated with an acid buffer and the supernate is incubated with an anti-CEA coated polystyrene bead. After washing, the bead is incubated with an anti-CEA/peroxidase conjugate. After a second washing, the activity of the enzyme bound to the solid phase is assayed after addition of a chromogenic substrate. This activity is proportional to the concentration of CEA in the serum sample. The characteristics of the assay are: (a) good sensitivity (around 0.25 microgram/L) and (b) satisfactory reproducibility (CV &lt; 11% within assay). There is little cross reactivity between CEA and molecules such as nonspecific cross-reacting antigens that are known for their high potential of cross reactivity. No nonspecific interference was encountered with anti-globulin factors. We compared results with this enzyme immunoassay kit with those by a radioimmunoassay provided by the Commissariat à l'Energie Atomique. The correlation (r) was 0.95 (p &lt; 0.001). The distribution of CEA values obtained for 1020 normal subjects is given. We conclude that the kit provides a simple and reliable procedure.
Evaluation of a new homogeneous enzyme inhibitor immunoassay of serum thyroxine with use of a bichromatic analyzer.
Authors: Finley P R , Williams R J , Lichti D A 
Published: January 2020

Abstract
We evaluated a new homogeneous enzyme immunoassay of thyroxine with use of a discrete analyzer (the ABA-100 Bichromatic Analyzer), modified with an auxiliary dispenser assembly. The assay is based on inhibition of hydrolysis of the substrate, acetyl-beta-(methylthio)choline iodide, by acetylcholinesterase (acetylcholine hydrolase; EC 3.1.1.7). Thyroxine covalently linked to a cholinesterase inhibitor irreversibly inhibits acetylcholinesterase, but if this thyroxine conjugate is bound to antibody it is not inhibitory. Seventy-five patients' samples may be analyzed in 1 h of instrument time. Precision and accuracy are excellent, results correlate well with those by radioimmunoassay, and there were no instances of confused clinical interpretation resulting from use of the proposed assay.
Specific serum pancreatic lipase determination, with use of purified colipase.
Authors: Hoffmann G E , Weiss L 
Published: January 2020

Abstract
We show that the turbidimetric method of Ziegenhorn et al. (Clin. Chem. 25: 1067, 1979) for determination of pancreatic lipase is not influenced by lipoprotein lipase. This improved specificity as compared to standard lipase methods is explained by the presence of purified colipase and the high concentration of bile acids in the substrate emulsion.
Bence Jones myeloma with a tetramer of kappa-type globulin in serum.
Authors: Gallango M L , Suinaga R , Ramírez M 
Published: January 2020

Abstract
We describe a case of Bence Jones multiple myeloma involving two kappa-type monoclonal proteins. One was isolated from serum, the other from both serum and urine. After biochemical and immunochemical analyses, we concluded that one of the proteins was a tetramer, present in serum but not in urine, whereas the other was a monomer, which was excreted in large amounts in the urine during the terminal stage of the disease.
Evaluation of baboon antiserum to carcinoembryonic antigen.
Authors: Haagensen D E , Cox C E , Dilley W G , Hensley M , Murdoch J , Newman E S , Wells S A 
Published: January 2020

Abstract
The common baboon (Papio), immunized with carcinoembryonic antigen (CEA), was found to form specific-site antibodies for CEA. The baboon antiserum does not recognize colon carcinoma antigen-III, but does demonstrate similar ionic strength effects to those previously described for goat antisera to the CEA-specific site(s). Baboon specific-site antibody for CEA can be used for radioimmunoassay of CEA in plasma and gives similar results to the commercial (Roche) goat anti-CEA.
Enzyme immunoassay of estriol in pregnancy urine.
Authors: Korhonen M K , Juntunen K O , Stenman U H 
Published: January 2020

Abstract
We describe an enzyme immunoassay for determination of total estriol in urine. Estriol covalently bound to horseradish peroxidase is used as tracer, and free and bound hormone are separated by precipitation with polyethylene glycol. The method can be used with either acid hydrolysis at 100 °C for 30 min or enzyme hydrolysis at 50 °C for 40 min; results by the former procedure are about 15% lower than results by the latter. Results were practically identical when we compared the enzyme immunoassay with a radioimmunoassay, using the same antiserum and method of hydrolysis. The day-to-day CV for three different concentrations was 10.7-12.0%, the within-series CV 6.6-8.6%. The additional time required for the enzyme reaction is compensated for by the rapid measurement of light absorbance. Thus this method is faster than radioimmunoassay when more than 25 samples are to be assayed.
New method for liquid-chromatographic measurement of erythrocyte protoporphyrin and coproporphyrin.
Authors: Salmi M , Tenhunen R 
Published: January 2020

Abstract
We describe a “high-pressure” liquid-chromatographic method for separating all the porphyrins in the heme biosynthetic pathway. The preliminary extraction and purification method is such that only erythrocyte porphyrins with fewer than five carboxyl groups, which includes protoporphyrin and the much smaller amount of coproporphyrin present, are measured. The porphyrins extracted from erythrocytes are chromatographically separated by use of a simple eluent system and fluorometrically detected.
Double-antibody immunoenzyme assay for human prostatic acid phosphatase.
Authors: Choe B K , Pontes E J , Dong M K , Rose N R 
Published: January 2020

Abstract
We compare the double-antibody radioimmunoassay (RIA) and immunoenzyme assay (IEA) for measuring the concentration of prostatic acid phosphatase in human serum. Experimental details and assay performance of the two methods are outlined. Mean values for 385 normal persons were 1.02 (SD 1.32) microgram/L by IEA, 2.69 (SD 1.8) microgram/L by RIA. Results of the two methods was highly correlated [r = 0.9813, y(RIA) = 0.35 x (IEA) + 0.42, p &lt; 0.001]. If we choose x- + 2 SD as the normal range, 3-10% false positives were seen.
Changes in transcutaneous oxygen tension during capillary blood-gas sampling.
Authors: Graham G , Kenny M A 
Published: January 2020

Abstract
With a Radiometer TCM-1 oxygen monitor, we followed the fluctuations in transcutaneous oxygen tension (ptcO2) during capillary blood collection from a heel prick. Thirty premature infants who presented with some respiratory compromise showed unpredictably increased (43 of 125 observations) or decreased (82 of 125 observations) values during this blood-sampling process. The fluctuation exceeded 10 mmHg in 61 observations and represented as much as -67% relative change. In general, ptcO2 values exceeded capillary pO2 values determined by standard blood-gas analysis. We investigated several aspects of capillary blood sampling to explain these observations. Because the induced response is a dynamic change, which continues throughout the collection process, we conclude that successive specimens will have different O2 tensions. Even if the capillary blood pO2 truly reflected paO2, the magnitude and direction of deviation from the patient's uncompromised O2 tension could lead to inappropriate management. We conclude that capillary blood specimens should not be used for pO2 determinations in newborns.
Analysis of fluorescence quenching data by the method of Levine.
Authors: Parsons D L 
Published: January 2020

Abstract
The quenching of intrinsic protein fluorescence upon binding of ligand is a relatively quick and easy method for studying these interactions. The method of Steiner et al. (J. Biol. Chem. 241: 560, 1966) and the method of Levine (Clin. Chem. 23: 2292, 1977) have been used by different authors to interpret the data obtained from fluorescence-quenching studies. However, as is shown here, the method of Levine is not strictly valid when the protein contains more than one binding site for the ligand. Therefore, this method only approximates binding constants from such data, with an accuracy that depends on the specific binding properties of the interactants.
Novel reagent and method for direct determination of chloride in serum with a centrifugal analyzer.
Authors: Law W T , Ertingshausen G 
Published: January 2020

Abstract
We report a novel reagent containing ferric perchlorate, perchloric acid, and polyoxyethylene (23) lauryl ether (Brij 35) with which the concentration of chloride in serum can be measured. We applied this reagent to use with a centrifugal analyzer (CentrifiChem 400) in a dynamic bichromatic procedure, resulting in broad linearity of the standard curve (0-180 mmol/L), short analysis time (1 min), and little interference from bilirubin, hemoglobin, turbidity, or bromide ions. The reagent is simple, contains no mercury, and the combination of low acid concentration and surfactant prevents serum protein precipitation. Precision is good (for x- = 93 mmol/L, CV = 1.55%), and results correlate well with those obtained by coulometry (r = 0.974).
Conductometric titration of hydrochloric acid in gastric juice.
Authors: van Zanten A P , van den Ende A 
Published: January 2020

Abstract
We describe a procedure for the determination of hydrochloric acid concentration in gastric juice by means of a conductometric titration of the 50-fold diluted sample with an aqueous ammonia solution. The conductometric method of endpoint indication leads to a definite location of the equivalence point in the titration of hydrochloric acid. The proposed method is simple and accurate and shows a good correlation with an accepted method for the measurement of gastric acidity.
Evaluation of an enzyme immunoassay for determining diazepam and nordiazepam in serum and urine.
Authors: Wallace J E , Harris S C , Shimek E L 
Published: January 2020

Abstract
We evaluated a commercially available enzyme immunoassay method for determining the concentration of total diazepam plus its active metabolite, nordiazepam, in small amounts of serum and urine. The coefficients of variation were 5% within assay and 8% between assay. Concentrations so measured for patients’ sera correlated well with those obtained both by gas chromatography with electron-capture detection and by liquid chromatography with ultraviolet detection. For urine samples, the correlation between values obtained by the enzyme immunoassay method and those for total diazepam/nordiazepam/oxazepam obtained by liquid chromatography was adequate for routine clinical toxicological use. The ability of the immunoassay to determine other benzodiazepines was also evaluated.
Semi-automated fluorometry of total estrogens in plasma during late pregnancy.
Authors: Goutte-Coussieu C , Sanchez D , Adessi G , Jayle M F 
Published: January 2020

Abstract
We describe a mechanized method for determining total estrogens in plasma during the last trimester of pregnancy. This method involves rapid enzymic hydrolysis, automatic extraction (in a tube) with cyclohexane/ethyl acetate, purification of the extracted material by anion-exchange chromatography on a disposable “mini-column” of Dowex AG1 X 2 (acetate form), and continuous-flow fluorometric quantification. Conditions of hydrolysis and extraction were studied. The mean within-day imprecision (CV) was 7% and between-day imprecision was 8.1%. Sensitivity was 75 nmol/L of plasma. Results are obtained in 4 h. The technique is quite suitable for routine determinations: 90 assays can be done by a team of three technicians in one working day.
Simultaneous liquid-chromatographic determination of three antiarrhythmic drugs: disopyramide, lidocaine, and quinidine.
Authors: Flood J G , Bowers G N , McComb R B 
Published: January 2020

Abstract
We report a common methodology for determining three antiarrhythmic drugs: disopyramide, lidocaine, and quinidine. Alkalinized serum and internal standard (p-chlorodisopyramide) are extracted into dichloromethane, the organic phase is evaporated, and the redissolved residue is injected onto a reversed-phase column (micron Bondapack C18). Quantitation is via peak-height ratios of analyte vs internal standard (as detected at 205 nm) referenced to a serum-based multiple-drug standard. A mobile phase of 30 mmol/L phosphate buffer and acetonitrile (72/28 by vol) is used. These conditions yiel; optimum separation and band symmetry for the analytes and some of their metabolites. Crucial factors in this simultaneous assay include pH of the mobile phase and injected solution, extraction time, and evaporation technique. Day-to-day precision (CV) for all drugs was less than 5%, and correlation with other assay techniques for each drug is reported. The method enables more efficient use of personnel and instrumentation without sacrificing analytical quality.
Simultaneous liquid-chromatographic determination of zinc protoporphyrin IX, protoporphyrin IX, and coproporphyrin in whole blood.
Authors: Gotelli G R , Wall J H , Kabra P M , Marton L J 
Published: January 2020

Abstract
We describe a method for simultaneously measuring concentrations of coproporphyrin, zinc protoporphyrin IX, and protoporphyrin IX in whole blood by liquid chromatography, with use of reversed-phase ion-pair system, fluorometric detection, and internal standardization. Each analysis requires 10 microL of whole blood and 15 min total analysis time. Analytical recovery ranged from 84 to 92%, day-to-day precision (CV) from 5 to 12%. Uroporphyrin, though not studied in detail, can also be detected by this method.
Personal and familial factors in cholesterolemia: criteria for selection of a reference population.
Authors: Steinmetz J , Panek E , Siest G 
Published: January 2020

Abstract
We studied factors affecting cholesterolemia in a presumably healthy population of 23 300 subjects, ages 20 to 59 years. Multiple-contingency tables were established, to quantify the information obtained by means of a factorial correspondence analysis. The relations between values for cholesterol and those for triglycerides, uric acid, and overweight were constant for all ages and both sexes. Cholesterolemia paralleled alcohol and tobacco consumption and arterial blood pressure. Use of oral contraceptives did not influence cholesterol values. We classified variation factors according to the statistical method of segmentation, by sex and age. This classification permitted us to establish criteria for excluding subjects from a population sampled with the aim of producing reference values for plasma cholesterol. The values of cholesterol for the 50th percentile were 5.40 mmol/L for men 20 to 39 years old and 5.79 mmol/L for those older than 40. For women, the 50th percentile values increased from 5.34 mmol/L between ages 20 to 39 to 5.92 mmol/L for ages 40 to 49 and to 6.51 mmol/L after 50.
Rate of decrease of glutamyltransferase and acid phosphatase activities in the human vagina after coitus.
Authors: Gohara W F 
Published: January 2020

Abstract
I studied the rate at which gamma-glutamyltransferase (EC 2.3.2.2) and acid phosphatase (EC 3.1.3.2) activities decrease in the healthy human vagina after coitus. Specimens from the coital and non-coital vagina, and from the rectum and buccal cavity, and pre-ejaculate lubricating fluid were also assayed for both enzymes. Prostatic acid phosphatase was determined with use of two substrates: thymolphthalein monophosphate and alpha-naphthyl phosphate (tartrate-inhibitable fraction). Glutamyltransferase was assayed with gamma-glutamyl-p-nitroanilide as substrate. All non-coital specimens were negative for glutamyltransferase activity; the activity of acid phosphatase varied with type of substrate and type of specimen. The equation y = a + (b/x) describes the decline in activity (y) of either acid phosphatase or glutamyltransferase in the vagina of healthy women post-coitally with time (x).
Amniotic fluid phosphatidylglycerol and phosphatidylinositol separated by stepwise-development thin-layer chromatography.
Authors: Mitnick M , DeMarco B , Gibbons J M 
Published: January 2020

Abstract
We describe a stepwise-development thin-layer-chromatographic technique for separating phosphatidylglycerol and phosphatidylinositol in samples of amniotic fluid. Plates are prepared from silica gel G slurried in a 50 g/L ammonium sulfate solution. Phospholipid phosphorus determination is not needed. Phospholipid phosphorus determination is not needed. Phosphatidylglycerol and phosphatidylinositol, measured densitometrically, are expressed as ratios to the sphingomyelin present. These ratios are correlated with the lecithin/sphingomyelin ratio and age of gestation in normal and abnormal pregnancies.