bluuebunny/crossref_metadata_2025_split huggingface dataset:
Liquid and lyophilized quality-control materials compared for use in continuous-flow analysis.
Authors: Elin R J , Gray B A 
Published: January 2020

Abstract
Using a Technicon SMAC continuous-flow instrument, we compared a liquid quality-control material ("Decision level 3," Beckman) with two different lyophilized quality-control materials. The variances for 19 analytes in the three materials were significantly greater for Decision than for the Ortho Abnormal and the Omega II lyophilized control sera (p less than 0.00001 for each comparison by the omnibus test). The imprecision for Decision was not due to incomplete mixing or carryover. The viscosity of Decision, however, was more than twice that of the two lyophilized control sera or of pooled human serum.
Simplified determination of serotonin in plasma by liquid chromatography with electrochemical detection.
Authors: Tagari P C , Boullin D J , Davies C L 
Published: January 2020

Abstract
This simplified determination of serotonin in human plasma involves "high-performance" liquid chromatography with electrochemical detection. Deproteinated samples of platelet-poor plasma are injected directly into the chromatograph without preliminary chromatographic purification. The limit of quantitative detection of serotonin in plasma is 5 nmol/L (equivalent to 250 fmol injected). Intra- and inter-assay CVs ranged from 5.6% to 7.7% and 3.5% to 14.9%, respectively, for concentrations of serotonin from 0.02 to 10.0 mumol/L. Results agreed well with those by spectrofluorometry, both for plasma standards (r = 0.985, range 100 nmol/L to 100 mumol/L) and for pathological samples obtained from four carcinoid syndrome patients (r = 0.964). The method is also applicable to the concurrent measurement of 5-hydroxytryptophan and 5-hydroxyindoleacetic acid.
Differences in radioimmunoassay results for thyroglobulin that affect management of patients with thyroid cancer.
Authors: Bayer M F , McDougall I R 
Published: January 2020

Abstract
We compared two commercial assays for measurement of serum thyroglobulin [Nuclear Medical Systems (NMS) and "CIS" (Damon Diagnostics)] with each other and with one developed at Stanford (J Clin Endocrinol Metab 49:557-564, 1979). The NMS assay is a competitive-binding RIA, the CIS and Stanford assays are two-site immunoradiometric assays. The kit standards varied in thyroglobulin concentration. The NMS standards differed in immunoreactivity from thyroglobulin in clinical specimens and from the other standards. Also, nonparallelism between standards and patients' sera in the NMS assay suggested a less-specific antiserum. Results by the CIS and Stanford assays correlated well (n = 120, r = 0.964), those by the NMS assay less strongly (n = 101, r = 0.855 vs CIS, r = 0.888 vs Stanford). Clinical evaluation in 50 patients treated for differentiated thyroid carcinoma (10 with metastases and 40 currently disease-free) indicated good agreement for positive results by the three assays. The CIS and the Stanford assay both gave high results (greater than or equal to 25 micrograms/L) in all 10 cases with metastases; the NMS RIA identified eight of these patients (thyroglobulin greater than or equal to 30 micrograms/L), but excluded two with anti-thyroglobulin autoantibodies. In subjects without disease, however, the percentage of undetectable thyroglobulin (negative result), as opposed to low measurable thyroglobulin (inconclusive result) varied considerably: 85% by CIS, 30% by NMS, and 75% by the Stanford assay.
Study of a mechanism responsible for anomalous results for free thyroxin by some analog assays for subjects with albumin deficiency.
Authors: Wilke T J 
Published: January 2020

Abstract
I examined the effect of albumin deficiency, as might occur in pregnancy and nonthyroidal illness, on four analog-based assays for free thyroxin (Amersham's Amerlex, Diagnostic Products Corporation's Coat-A-Count "one-step," Clinical Assays' Gammacoat "one-step," and Corning's Immophase "single-step"). In subjects with albumin deficiency per se, Amerlex and Coat-A-Count results for free thyroxin were not significantly different from normal, whereas free thyroxin values by Gammacoat and Immophase assays were lower than that of the control. Furthermore, in the albumin-deficient group, the mean amount of thyroxin associated with antisera in each assay was significantly higher than that of the control and correlated well with the degree of decrease in free thyroxin. I conclude that subnormal results for thyroxin by analog assays, in euthyroid patients with albumin deficiency, is a function of the specific assays and is not a characteristic of analog assays per se. In addition, the study suggests that albumin deficiency alters the distribution between thyroxin and its binders in all four analog assays, but only in the Gammacoat and Immophase methods is this alteration sufficiently large as to distort assay results.
Homogeneous enzyme immunoassay for cortisol with a centrifugal analyzer.
Authors: Izquierdo J M , Quirós A , Alvarez-Uría J , Sotorrío P 
Published: January 2020

Abstract
We determine serum cortisol by a homogeneous enzyme immunoassay in the Cobas Bio centrifugal analyzer. To unbind cortisol from its protein complex, serum is treated for 15 min with an acidic solution. The reaction then proceeds automatically in the analyzer at 37 degrees C. To 50 microL of sample mixture is added 125 microL of reagent (cortisol antibodies, glucose 6-phosphate, and NAD+). This mixture is incubated for 60 s, after which 25 microL of a cortisol derivative labeled with glucose 6-phosphate is added; the increase in absorbance is monitored at 340 nm. The standard curve was linear from 10 to 500 micrograms of cortisol per liter. Within-assay precision (CV) varied from 0.2 to 0.6%, between-assay precision from 6.2 to 10.6%. Analytical recovery ranged from 100 to 103%. Results for control samples deviated from target values by 1.4 to 7.8%. Results compared well with those by radioimmunoassay. The method is reliable and practicable and will usefully replace previous routine methods for serum cortisol.
Chromatograph with external column evaluated for determining breath hydrogen in clinical studies.
Authors: Rosado J L , Torres L , Solomons N W 
Published: January 2020

Abstract
A novel breath-hydrogen analyzer involving an external chromatographic column in the form of a cartridge packed with molecular-sieve material and dessicant is described. The instrument incorporates a sintered SnO2 solid-state sensor into the detector, which registers a change in electrical potential in response to the adsorption of reducing gases; ambient room air is drawn through an activated charcoal filter by a small, internal pump and used as the carrier gas. Once calibrated with a gas of known H2 concentration, a digital meter registers the concentration of H2 in an unknown sample of breath air. The response is linear with concentration up to 160 microL/L. The external column is both necessary and effective for screening out contaminating reducing gases. The correlation coefficient for 250 gas samples measured simultaneously with an external-cartridge instrument and with an internal column chromatography is greater than 0.99. Results by the new analyzer corresponded 100% with those by the conventional machine for detecting carbohydrate malabsorption; for diagnosing efficient carbohydrate absorption, results by the two instruments agreed for 96% of the tests.
The distribution of chymotrypsin within the feces and description of a new device for the preparation of stool samples.
Authors: Kaspar P , Neumann U 
Published: January 2020

Abstract
We measured the distribution of chymotrypsin within feces by comparing duplicate 100-mg stool aliquots from 48 stool specimens. For practical purposes, the distribution of the enzyme in stool appears sufficiently homogeneous to assure representative results even from 100-mg stool aliquots. Given this likelihood, we have developed a new disposable device that measures 100-mg stool aliquots hygienically, prepares this material for shipping by mail, homogenizes and suspends the stool sample, and facilitates centrifugation of the fecal suspension, all within the same instrument. Performance studies with this new device revealed that stools of different consistency can be measured out precisely and conveniently by volume. The difference in the specific weight of different stools appears to be so low that for practical purposes a 100-mg mass of stool can be weighed out by volume.
Effect of heat and sodium dodecyl sulfate on solubilization of proteins before two-dimensional polyacrylamide gel electrophoresis.
Authors: Hodges S C , Hirata A A 
Published: January 2020

Abstract
To solubilize biological samples, sodium dodecyl sulfate (SDS) frequently is added and the mixture heated at 70-100 degrees C. However, two-dimensional polyacrylamide gel electrophoresis of a single protein after SDS treatment has not been reported. When rabbit-muscle creatine kinase was so run, we saw considerable difference in the gel staining pattern for the heated and nonheated enzyme dissolved in the SDS solution. After heating for 10 min at 95 degrees C the number of silver-stained spots apparent increased, and staining of several spots intensified. After 60 min, most of the discrete spots disappeared. Evidently the peptide backbone had been hydrolyzed. When the enzyme was simply left at room temperature for four days, the effects were similar. Appearance of new spots and loss of spots apparently are caused by heating alone but are intensified by SDS. Experiments with human serum albumin yielded similar results.
A new succinylcholine-based assay of plasma cholinesterase.
Authors: Abernethy M H , George P M , Melton V E 
Published: January 2020

Abstract
We describe a new method for measuring the in vitro rate of hydrolysis of the muscle relaxant succinylcholine. This substrate is hydrolyzed by plasma cholinesterase (EC 3.1.1.8). The resulting choline is determined by measuring the hydrogen peroxide formed on its oxidation by choline oxidase (EC 1.1.3.17). This is done by use of phenol and aminoantipyrine coupled to peroxidase, and yields an intense chromophore, Amax 500 nm. The assay requires 0.1 mL of plasma, and is precise and specific. The CV was 2.7% within run, 7.3% between run. For the usual (U variant) enzyme the Km is 53 mumol/L. Enzyme activity is removed by anticholinesterase antiserum, and is inhibited by dibucaine with a Ki of 2 mumol/L. Ten samples can be assayed in duplicate in an hour. This method is suited to routine use in any laboratory that has a simple spectrophotometer. The mean activity in 11 individuals with the cholinesterase phenotype UU was 105 U/L, for seven UA heterozygotes 61 U/L, and for three AA homozygotes 4 U/L. To the extent allowed by extrapolation from in vitro to in vivo results, this method should increase diagnostic accuracy and may directly predict duration of succinylcholine-induced apnea.
Plasma prolidase activity: a possible index of collagen catabolism in chronic liver disease.
Authors: Myara I , Myara A , Mangeot M , Fabre M , Charpentier C , Lemonnier A 
Published: January 2020

Abstract
We describe here an easy method of determining prolidase (EC 3.4.13.9) in plasma after preincubation with Mn2+ for 24 h at 37 degrees C to maximize prolidase activity. The mean activity in 338 patients who were either in hospital or outpatients was 900 U/L +/- 520 (2 SD), unrelated to sex or age. In 25 of these 338 samples tested, prolidase activity was between 1500 and 2000 U/L. It exceeded 2000 U/L in eight, all of whom were patients with chronic liver disease. Plasma prolidase activity was normal in cytolytic syndromes such as liver or heart disease. Of the 27 patients with cirrhosis, only five exhibited prolidase activity greater than 2000 U/L. Plasma prolidase activity was uncorrelated with six biochemical indexes to liver function (the aminotransferases, alkaline phosphatase, glutamyltransferase, total bilirubin, and serum albumin) or with the degree of cirrhotic fibrosis. We believe that plasma prolidase activity may be high only in the early stage of fibrosis. This hypothesis would be consistent with the data on rat-liver collagenolytic activities during CCl4 administration. Monitoring of plasma prolidase activity might be useful in evaluating fibrotic processes in chronic liver disease in the human.
Determination of creatine kinase MB activity with the Du Pont aca: interferences from the sample matrix.
Authors: Stein W , Bohner J 
Published: January 2020

Abstract
During the last three years we and other have observed discrepancies between results for creatine kinase isoenzyme MB as measured with the mechanized ion-exchange chromatographic method in the Du Pont aca and those by other techniques. These observations prompted us to investigate the influence of the matrix on the Du Pont CK-MB assay. We conclude that, apart from possible interferences by CK-MM, CK-BB, and both types of macro CK, the aca will give apparent CK-MB activities that are directly related to protein concentration and inversely related to sodium chloride concentration. Practical consequences for the routine and emergency laboratories are: no diluted samples are allowed; application is restricted to samples from patients suspected of acute myocardial infarction which show upper-normal total CK activity; and multiple timed samples are run, in order to recognize the typical change in enzyme pattern with time.
Improved diagnosis of classical vs atypical phenylketonuria by liquid chromatography.
Authors: Matsubara Y , Heininger J A , Lin Y Y 
Published: January 2020

Abstract
Atypical phenylketonuria among infants with hyperphenylalaninemia must be promptly diagnosed and differentiated from classical phenylketonuria, because these patients require different treatment to prevent irreversible neurological damage. Measurement of pteridines in urine by liquid chromatography has been widely used for this purpose. Here we report a rapid, simplified liquid-chromatographic method for simultaneously measuring urinary biopterin, neopterin, and creatinine. Unlike previous methods, this method involves neither tedious cleanup procedures nor special equipment.
Enzymatic determination of D-mannose in serum.
Authors: Soyama K 
Published: January 2020

Abstract
A new and simple enzymatic assay for measuring D-mannose in serum is described. Endogenous glucose is eliminated from serum by use of glucose oxidase (EC 1.1.3.4) and catalase (EC 1.11.1.6). D-Mannose concentration is calculated from the increase in NADH formation after mannosephosphate isomerase (EC 5.3.1.8) is added. This increase is a result of coupling the following series of enzymes: hexokinase (EC 2.7.1.1), glucosephosphate isomerase (EC 5.3.1.9), and glucose-6-phosphate dehydrogenase (EC 1.1.1.49, NAD+-dependent). The study included subjects who were healthy volunteers and patients with suspected or proven fungal infections.
Automated kinetic method for D-3-hydroxybutyrate in plasma or serum.
Authors: McMurray C H , Blanchflower W J , Rice D A 
Published: January 2020

Abstract
This assay for 3-hydroxybutyrate in plasma or serum, based on kinetic initial-rate techniques, has been optimized with respect to initial rate and linearity as follows: pH 8.5, hydroxybutyrate dehydrogenase 62.5 U/L, and NAD+ concentration 20 mmol/L. We have used the assay satisfactorily with both the Gilford 103 and Hitachi 705 discrete analyzers, obtaining results that compare well with those by a segmented-flow method. Within-assay precision (CV) varied from 7.8 to 0.6%, depending on both the analyzer used and on the concentration of 3-hydroxybutyrate. Analytical recovery was also dependent on 3-hydroxybutyrate concentration, varying from 99% at 2 mmol/L to 91% at 9.5 mmol/L. Lactate dehydrogenase/lactate interference in this direct assay is eliminated by incorporating oxalate in the assay reagents. Hydrazine, commonly used in equilibrium methods of analysis for 3-hydroxybutyrate, produced no significant advantage in this assay and was omitted. The mixed reagents for the assay are stable at 4 degrees C for at least a week. The advantages of analysis for this metabolite may now be realized, so that clinical and subclinical ketosis can be identified in humans and animals.
Use of high-resolution proton nuclear magnetic resonance spectroscopy for rapid multi-component analysis of urine.
Authors: Bales J R , Higham D P , Howe I , Nicholson J K , Sadler P J 
Published: January 2020

Abstract
Numerous low-Mr metabolites--including creatinine, citrate, hippurate, glucose, ketone bodies, and various amino acids--have been identified in 400- and 500-MHz proton nuclear magnetic resonance (1H NMR) spectra of intact human urine. The presence of many of these was related to the specific condition of the donors: humans in different physiological states (resting, fasting, or post-exercise) and pathological conditions (e.g., diabetes mellitus, cadmium-induced renal dysfunction). We have also monitored the metabolism of simple nonendogenous compounds (methanol and ethanol) and of acetaminophen. The pH-dependencies of the NMR chemical shifts of some urine components are reported. Our studies show that high-resolution 1H NMR spectroscopy provides a fast, simple method for "fingerprint" identification of urinary compounds. In some cases, analytes can be quantified by standard additions or by comparing integrated peak areas for the metabolites with those for creatinine. Determinations of creatinine by 1H NMR spectroscopy compared well with those by an independent chemical assay based on the Jaffé reaction.
A thyrotropin radioimmunoassay kit evaluated vs two reference assays.
Authors: Bigos S T , Pekary A E , MacLean J , Pierce C E , Reed A W , Hershman J M 
Published: January 2020

Abstract
We evaluated a double-antibody radioimmunoassay kit for thyrotropin that includes calibrators prepared in a matrix of human serum and involves overnight nonequilibrium. Results were compared with those from two reference assays for thyrotropin. The range of within-assay CVs for the kit for thyrotropin values between 0.9 and 2.4 milli-int. units/L was 2.2 to 5.3%, that for between-assay CVs was 8.3 to 30%. The estimated minimum detectable concentration of thyrotropin was 0.6 milli-int. unit/L. We saw no cross reactivity with human choriogonadotropin by any of 48 sera from pregnant women. The original lot of serum specified as thyrotropin-free contained small but measurable amounts of thyrotropin; a second lot did not. Clinical data generated with the kit and the reference assays correlated well and were consistent with the clinical status of various categories of patients.
Digoxin-like immunoreactivity in normal human plasma and urine, as detected by a solid-phase radioimmunoassay.
Authors: Balzan S , Clerico A , Grazia del Chicca M , Montali U , Ghione S 
Published: January 2020

Abstract
Reports on the presence of digoxin-like immunoreactive substance(s) (DLIS) in the plasma and urine of several animal species and a few human test subjects prompted us to undertake to confirm the presence of DLIS in plasma and urine of normal persons and to investigate some characteristics of this antibody-DLIS binding. For this purpose we used a modified radioimmunoassay kit involving antidigoxin antibody-coated test tubes and 125I-labeled digoxin to measure DLIS in urine and concentrated plasma of ostensibly healthy subjects. In 12 separate experiments with plasma the mean sensitivity was 5.12 (SD 1.11) pg per tube, expressed as digoxin. There was no significant cross reactivity with human serum albumin in concentrations up to 200 g/L. The mean DLIS value (in digoxin equivalents) for plasma from 24 normal subjects was 33.58 (SD 14.24) ng/L. Its mean concentration in urine from five subjects was 315.00 (SD 91.38) ng/L.
Tartrate-resistant acid phosphatase in serum of cancer patients.
Authors: Lam K W , Dannaher C , Letchford S , Eastlund T , Li C Y , Yam L T 
Published: January 2020

Abstract
Tartrate-resistant acid phosphatase activity determined by enzyme immunoassay was higher in the serum of cancer patients than that in normal blood donors. The highest activity was found among patients having malignancy metastatic to bone. The classic colorimetric method showed a broad range of values among normal blood donors, and the contrast between normal and cancer patients was less obvious. Most of the cancer patients had normal to low alkaline phosphatase activities.
Selenium and other elements in human maternal and umbilical serum, as determined simultaneously by proton-induced X-ray emission.
Authors: Hyvönen-Dabek M , Nikkinen-Vilkki P , Dabek J T 
Published: January 2020

Abstract
Using PIXE (proton-induced X-ray emission), we simultaneously determined the concentrations of Se, Ca, Fe, Cu, Zn, Br, and Pb in blood serum from 56 pregnant women, 25 healthy controls, and 31 others with twin pregnancy or some complicating condition (diabetes, hypertension, epilepsy, hepatosis gravidarum, pre-eclampsia, small baby), and in cord-blood serum from 21 newborns. Pellets, pressed from the serum samples after addition of yttrium as an internal standard, mixing, and evaporating at 30 degrees C with or without reduced pressure (less than 1 kPa), were bombarded by 2.2 MeV protons from a Van de Graaff accelerator in the air and the induced X-rays collected by a Ge(Li) detector. Relative to mean Se values for early six- to 12-week pregnancy (0.045 ppm), those for 35-42 week pregnancy (0.028 ppm) were low (p less than 0.001). Umbilical cord blood serum showed even lower values (0.016 ppm, p less than 0.001)--findings in harmony with the incidence pattern of Keshan cardiomyopathy. Pb crossed the placenta; values for cord serum were not significantly different from those in pregnancy serum. Cu, Zn, Fe, and Ca showed the significant expected patterns in the different groups. Compared with the late-pregnancy controls, Fe was high in mothers of small-birth-weight babies (1.70 ppm, p less than 0.02). Br was high in pre-eclampsia (3.59 ppm, p less than 0.05) and mothers with twins (3.61 ppm, p less than 0.05).
Interferences with potentiometry of CO2 in the Ektachem 400 Analyzer.
Authors: Steelman M , Smith C H , Menon A , Thach B T , Hillman R E , Landt M 
Published: January 2020

Abstract
We have investigated the Kodak Ektachem 400 Analyzer procedure for CO2 for interferences from benzyl alcohol, benzoic acid, and several compounds structurally similar to benzoic acid. Benzoic acid in plasma, at concentrations found in neonates intoxicated with benzyl alcohol, caused a large increase in the results for CO2, as did substantially above-normal concentrations of certain fatty acids and keto-acids, and toxic concentrations of aspirin. We observed a correlation between increasing benzoic acid concentrations (up to 17 mmol/L) and falsely increasing CO2 values (greater than 47 mmol/L) obtained with the Ektachem Analyzer for samples from a neonate in the intensive-care unit, who was receiving benzyl alcohol-preserved saline solutions. Although the Ektachem CO2 procedure is simple and rapid, and in most cases accurate, questionable results are occasionally encountered, as indicated by a low anion gap or a measured CO2 exceeding that calculated from blood gas measurements. Such results require the use of another method for verification.