bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fluoroimmunoassay of digitoxin in serum.
Authors: Al-Hakiem M H , Simon M , Mahmod S , Landon J 
Published: January 2020

Abstract
This fluoroimmunoassay for digitoxin in serum involves use of a sheep antiserum to digitoxin coupled to magnetizable solid-phase particles and fluorescein-labeled 3-O-succinyl digitoxigenin as tracer. Sodium salicylate blocks binding of the drug by binding proteins, and endogenous fluorophores and other interfering components in serum samples are reliably and completely removed at the separation and wash steps, which are facilitated by magnetic sedimentation. The method is sufficiently sensitive, precise, and specific for application to routine monitoring of digitoxin therapy, and results correlate closely (r = 0.992) with those of an established radioimmunoassay.
Effect of anti-thyroxin autoantibodies on radioimmunoassay of free thyroxin in serum.
Authors: Konishi J , Iida Y , Kousaka T , Ikekubo K , Nakagawa T , Torizuka K 
Published: January 2020

Abstract
Serum thyroxin was nearly or completely undetectable by radioimmunoassay in an elderly patient with Graves' disease being treated with methimazole. Abnormal binding of thyroxin to antibodies of the IgG variety was shown, the association constant of the complex being 8.0 x 10(8) L/mol and the binding capacity 6.3 nmol/g of IgG. The effect of the antibody on results of radioimmunoassay of free thyroxin was studied with three commercial kits, two of which (Clinical Assays and Damon Diagnostics) gave essentially the same values as did equilibrium dialysis. The third (Amersham International) gave falsely high results because the 125I-labeled thyroxin derivative used in the kit was bound by the autoantibody.
Flameless atomic absorption spectrophotometry of selenium in whole blood.
Authors: Tulley R T , Lehmann H P 
Published: January 2020

Abstract
In this method of analysis for selenium in whole blood by flameless atomic absorption spectrophotometry, 1 mL of sample is first digested with perchloric and nitric acids. After reduction and neutralization, the sample is reacted with 2,3-diaminonaphthalene, and the product is extracted into toluene. Twenty microliters of the extract is injected into the graphite furnace of a flameless atomic absorption spectrophotometer, along with 20 microliters of a 1.0 g/L cupric nitrate solution. Blood-based standards are used to establish the standard curve. The amount of selenium required to give an absorbance of 0.0044 is 5.3 micrograms/L. Precision is good, recovery excellent. The extract is stable for 24 h.
Simple, reliable chromatographic measurement of oxalate in urine.
Authors: Di Corcia A , Samperi R , Vinci G , D'Ascenzo G 
Published: January 2020

Abstract
In this assay for oxalate in urine, oxalate is adsorbed from the urine onto graphitized carbon black (Carbopack B). After desorption and removal of the solvent, oxalic acid is gas-chromatographically measured after being derivatized with BF3/methanol. Chromatography is on Carbopack B/polyethylene glycol (Mr 20000), 93.7/6.3 by weight. The lower limit of detection of urinary oxalate is about 3 mg/L (CV less than or equal to 3.6%). A series of oxalate determinations in 24-h urine samples of 15 subjects gave a mean of 47.1 (SD 15.4) mg/24 h, with an analytical recovery of 97.4% (SD 3.0%, range 93.6-102.4%). Total analysis time for one sample is about 2 h.
Determinations of amylase isoenzymes in serum by use of a selective inhibitor.
Authors: Huang W Y , Tietz N W 
Published: January 2020

Abstract
A simple, rapid screening procedure for determining the relative amounts of pancreatic (P)- and salivary (S)-type amylase in serum is presented, involving incorporation of a selective inhibitor (from wheat-germ) into commercially available BMD Single-Vial Amylase and Beckman Enzymatic Amylase-DS procedures for manual and automated isoamylase measurements. Optimal concentrations of inhibitor inhibit the S-type amylase fraction by 87-88%. In contrast, the pancreatic fraction is inhibited by only 19% in either the manual or automated methods. The degree of inhibition is constant for amylase activities up to at least 520 U/L. Use of the ratio (P-amylase/total amylase activity) X 100 helps differentiate between hyperamylasemia caused by S-type or P-type amylase. In preliminary studies, patients with pancreatitis showed a ratio greater than 70%.
Enzymic and chemical-extraction determinations of free fatty acids in serum compared.
Authors: Demacker P N , Hijmans A G , Jansen A P 
Published: January 2020

Abstract
We compared an enzymic test kit for determination of free fatty acids in serum (NEFA C-test, WAKO) with two modifications of a chemical extraction procedure, I (Clin. Chim. Acta 43: 317-320, 1973) and II (Clin. Chim. Acta 80: 327-332, 1977). All three procedures are specific for long- and medium-chain fatty acids. Short-chain fatty acids, some keto acids, and phospholipids did not interfere. Added fatty acid was quantitatively accounted for in all methods. Results obtained with the enzymic method and II did not differ significantly, whereas the results by I were about 10% lower. The concentration of NaCl in the copper reagent, but not the kind of solvent used to dissolve the standard, influenced the accuracy of the chemical methods. In the enzymic procedure, hydrolysis of triglycerides during incubation is unlikely to be the reason for too-high values. The precision of all three procedures is acceptable for use in clinical laboratories.
Evaluation of three minicolumn procedures for measuring hemoglobin A1.
Authors: Hammons G T , Junger K , McDonald J M , Ladenson J H 
Published: January 2020

Abstract
We have evaluated three commercially available column-chromatographic methods (Isolab, Helena, and Bio-Rad) for the determination of "fast" hemoglobin (HbA1). All three methods correlated with HbA1c measurements by "high-performance" liquid chromatography for 121 samples from diabetic patients, with the Isolab method showing the highest correlation (r = 0.921). The Isolab and Helena methods gave results that were linear with proportions of HbA1 as great as 30%; results by the Bio-Rad method were slightly nonlinear at values greater than 15%. The Isolab method showed better within- and between-assay precision (CV) than the other two methods and was considered the simplest to perform by each of four different technologists. We recommend use of the Isolab method over the other two tested and believe that this procedure will be valuable for monitoring long-term glycemic control in diabetic patients.
Methylmalonic acidemia with the unusual complication of severe hyperglycemia.
Authors: Boeckx R L , Hicks J M 
Published: January 2020

Abstract
We describe a case of neonatal methylmalonic acidemia with the unusual complication of severe, insulin-resistant hyperglycemia. Methylmalonic acidemia, an inherited metabolic disease affecting the catabolism of propionic acid, is manifested by persistent metabolic acidosis, urinary excretion of large amounts of methylmalonic acid, and occasionally by hypoglycemia. Severe and persistent metabolic acidosis and hyperglycemia, despite large doses of insulin, were observed in this infant, who excreted large amounts of methylmalonic acid. The diagnosis of methylmalonic acidemia was confirmed by gas chromatography-mass spectroscopy, but the patient died before the defect in glucose tolerance could be delineated. We hypothesize that, in addition to the methylmalonic acidemia, the patient may have had an insulin-receptor defect, which was manifested as an inappropriate response to endogenous and exogenous insulin.
Organic electrochemical techniques having potential clinical application.
Authors: Durst R A , Blubaugh E A , Bunding K A , Fultz M L , MacCrehan W A , Yap W T 
Published: January 2020

Abstract
The Organic Electrochemistry Group at the National Bureau of Standards is pursuing several avenues of research of potential application to problems of clinical chemists. With one development, electrochemical detectors for liquid chromatography, organomercury species can be determined in biological tissues and other matrices. Spectroelectrochemistry is being used to characterize the redox behavior of metal complexes of bleomycin, an antitumor drug. Chemically modified electrodes are being developed as selective electrocatalytic sensors for organohalogen compounds and may lead to new sensors for clinically important analytes. Surface-enhanced Raman spectroscopy is helping characterize the polymer films used to modify the electrode surfaces. Another sensor is being developed for the detection of carboxylic acids: after the photocatalytic oxidation of the acids at a semiconductor electrode, the carbon dioxide produced is subsequently determined with a flow-through gas-sensing electrode. Finally, mathematical modeling may provide a better understanding of the fundamental processes involved in several of the above techniques.
Polymer-membrane electrode-based potentiometric sensing of ammonia and carbon dioxide in physiological fluids.
Authors: Meyerhoff M E , Fraticelli Y M , Greenberg J A , Rosen J , Parks S J , Opdycke W N 
Published: January 2020

Abstract
Several new electrochemical devices designed for detecting ammonia and carbon dioxide in physiological samples have in common the elimination of the fragile glass pH internal electrode used in the conventional Severinghaus-design potentiometric gas sensors. In one new approach, the pH glass electrode can be replaced with a neutral carrier-based polymer-membrane pH electrode. Alternatively, to improve response characteristics and selectivity, we have used ion-selective polymer membranes responsive to ammonium and carbonate as internal sensing elements in conjunction with appropriate internal buffer reagents. The use of inner polymer membranes rather than glass membranes enables the fabrication of essentially disposable devices having rapid response times. In addition, we have constructed automated continuous-flow NH3- and CO2-sensing systems involving novel tubular forms of the polymer-membrane electrodes and a simple flow-through gas dialysis arrangement. The polymer electrode-based systems described offer many unique and practical advantages over existing gas-sensing units.
Effect of temperature on the p50 value for human blood.
Authors: Samaja M , Melotti D , Rovida E , Rossi-Bernardi L 
Published: January 2020

Abstract
We investigated the effect of temperature (19, 30, 37, and 43 degrees C) on the p50 value for normal human blood at pco2 = 5.72 kPa (43 mmHg), at various pHs (range 7.0 to 7.6) and molar ratios of [2,3-diphosphoglycerate]/[Hb4] (range 0.4 to 2.4). The d(log p50)/d(pH) coefficient varied from 0.39 at 19 degrees C to 0.35 at 43 degrees C. The relationship between log p50 and 1/T (T = degrees Kelvin) was linear under the experimental conditions used, and the d(log p50)/d(1/T) coefficient varied between -2138 at pH 7.0 and -2162 at pH 7.6, independent of the concentration of 2,3-diphosphoglycerate. Assuming that the effect of pco2 on the p50 value is the same at 19, 30, and 43 degrees C as at 37 degrees C, one can use the reported coefficients to calculate the p50 value for normal human blood under conditions of temperature, pH, pco2, and 2,3-diphosphoglycerate concentrations prevailing under physiological and pathological conditions. The p50 value calculated by empirical equations, taking into account the effect of temperature, correlated well with the values for p50 determined experimentally (y = 0.9774x + 0.453; r = 0.998; n = 60), with an SD of 52 Pa (0.39 mmHg).
Evaluation of a colorimetric method for determination of glycosylated hemoglobin.
Authors: Standefer J C , Eaton R P 
Published: January 2020

Abstract
We evaluated a colorimetric assay for glycosylated hemoglobin to determine the effects of several variables --oxalic acid concentration, extraneous glucose, hemoglobin concentration, hydrolysis interval, and 5-hydroxymethylfurfural destruction--and the precision. The interference seen when the blood glucose concentration exceeds 2.0 g/L (11 mmol/L) can be eliminated by washing the erythrocytes with 9 g/L saline. The accuracy of this assay is not influenced by hemoglobin concentrations from 80 to 150 g/L. The background nonspecific color, although substantial, is similar from sample to sample. After a 5-h hydrolysis at 100 degrees C, about 85% of the hexose is released, and the analytical recovery of 5-hydroxymethylfurfural is constant over a wide range of glycosylated hemoglobin concentrations. The 5th to 95th percentile reference interval for a population of 65 nondiabetic individuals was 4.6 to 6.1 mol per 100 mol of total hemoglobin. The range of values for a population of 85 diabetic patients was 6.9 to 20.4 mol per 100 mol.
Measurement of nifedipine in plasma by gas--liquid chromatography and electron-capture detection.
Authors: Hamann S R , McAllister R G 
Published: January 2020

Abstract
In this method for measuring nifedipine, a calcium-channel inhibitor now widely used in the treatment of cardiovascular disease, the drug is extracted from plasma under basic conditions into toluene, and an aliquot of the extract is injected directly into a gas chromatograph equipped with an OV-101 column and an electron-capture detector. The standard curve is linear between 1 and 100 micrograms/L; the assay measures not only nifedipine, but also a major metabolic product (found only after oral administration of the parent drug) and photodegradation products. The procedure is rapid and adequately sensitive for routine use in clinical monitoring of nifedipine in plasma.
Solid-phase radioimmunoassay for human placental lactogen in serum.
Authors: Samuel G , Sivaprasad N , Shah K B , Mani R S 
Published: January 2020

Abstract
We report a solid-phase radioimmunoassay for human placental lactogen, in which antibody-coated polystyrene tubes and polyurethane sponges are used. Incubation time and temperature, ionic strength of buffer, and nonspecific adsorption have been evaluated for optimum conditions required for routine clinical assays. The validity of the assay technique has been ascertained by its specificity, reproducibility, and recovery. The sensitivity of this method is 0.4 ng of placental lactogen per assay tube.
Cross reactivity of the EMIT digoxin assay with digoxin metabolites, and validation of the method for measurement of urinary digoxin.
Authors: Linday L , Drayer D E 
Published: January 2020

Abstract
In evaluating the EMIT (Syva Co.) digoxin assay, we found no cross reactivity between dihydrodigoxin, the major digoxin metabolite, and the EMIT digoxin antibody from two different lots. However, the antibody does cross react, essentially completely, with the digoxin hydrolysis metabolites digoxigenin, digoxigenin mono-digitoxide, and digoxigenin bis-digitoxide. The EMIT method can be used to measure digoxin in urine diluted at least 50- to 100-fold with digoxin-free human plasma; the inter-assay coefficient of variation of this assay is 6%. In addition, we validated the manual EMIT serum digoxin assay, using external ("TRI-rac") quality controls.
Frequency of hypomagnesemia in hypokalemic states.
Authors: Boyd J C , Bruns D E , Wills M R 
Published: January 2020

Abstract
Although both hypokalemia and hypomagnesemia have been linked with life-threatening cardiac arrhythmias, published studies disagree regarding the frequency of simultaneously low serum potassium and magnesium concentrations. To investigate the possible associations between the concentrations of these ions in serum, we carried out a retrospective study of all paired magnesium-potassium measurements reported from our laboratory during two separate two-week periods. Of 963 paired measurements in 421 patients, 12% of the samples were hypokalemic and 26% were hypomagnesemic. The frequency of hypomagnesemia was significantly greater in hypokalemic samples (38%) compared with nonhypokalemic samples (25%). The potential clinical importance of this relationship requires further investigation.
Macro creatine kinase types 1 and 2: clinical significance in neonates and children as compared with adults.
Authors: Wu A H , Herson V C , Bowers G N 
Published: January 2020

Abstract
We examined the case histories of seven pediatric patients (ages four days to 12 years) whose sera showed significant activities of "macro" creatine kinase (CK; EC 2.7.3.2): two cases of macro CK type 1 (CK-BB isoenzyme bound to IgG) and five cases of macro CK type 2 (polymeric complexes of mitochondrial CK). The diagnoses of the two children with macro CK type 1 were similar to those in 55 adult patients with this form of CK found earlier during screening of a population of 5000. Macro CK type 1 has generally been noted only in older women; this is the first report of it in children. In four of the five cases of macro CK type 2 we found in children, myocardial muscle damage was clinically evident. In contrast, the 26 cases of adults with macro CK type 2 found during the same screening generally had neoplasms, most with metastases to the liver. We suggest that the finding of macro CK type 2 is an indicator of cellular necrosis; in pediatric cases with myocardial damage the associated conditions may be reversible but in adults with malignancies the finding is associated with an extremely poor prognosis.
Falsely high serum creatinine concentration associated with severe methanol intoxication.
Authors: WU A H , Stout R , McComb R B 
Published: January 2020

Abstract
A case of severe methanol intoxication (1300 mg/L) was associated with markedly increased serum creatinine (490 mg/L) despite normal urea values and the absence of any other signs of renal disease. These values declined progressively to normal, and the patient recovered with no visual impairment. Additional laboratory experimentation suggested that the high creatinine value was probably ascribable to some unknown foreign material(s) in the patient's blood that reacted with the alkaline picrate used in the measurement of creatinine. One of the presumed metabolites of methanol, formaldehyde, reacts with creatinine but the product does not react with picrate. We believe that the foreign material was derived from either commercial preparations of methanol or contaminants in the patient's drinking water.
On the calculation of a "reference change" for comparing two consecutive measurements.
Authors: Harris E K , Yasaka T 
Published: January 2020

Abstract
We describe a statistical method for calculating a "reference change," defined as that difference between two consecutive test results in an individual that is statistically significant in a given proportion of all similar persons. By allowing for variation in within-person variances, this procedure computes a reference change that is more specific (i.e., less prone to false positives) than that obtained directly from the distribution of observed differences between measurements. Moreover, the method may easily be extended to a test for trend in three successive measurements. The method has been applied to semi-annual measurements of serum calcium and alkaline phosphatase in 698 men and women enrolled in a large health-maintenance program. We believe that these ideas may also be usefully applied to successive laboratory tests in carefully defined patient populations--but this introduces special problems, which are discussed briefly.
A diazo-based dry film for determination of total bilirubin in serum.
Authors: Dappen G M , Sundberg M W , Wu T W , Babb B E , Schaeffer J R 
Published: January 2020

Abstract
We have prepared a diazo-based dry film for use in determining total serum bilirubin. On a transparent support are a buffered gelatin layer containing a polymeric quaternary amine (the mordant) and a white, reflective spreading layer that contains all of the components necessary for detection of bilirubin. The method is based on the use of dyphylline and Triton X-100 surfactant to dissociate bilirubin from albumin and subsequent reaction of bilirubin with a diazonium salt [4-(N-carboxymethylsulfamyl)benzenediazonium hexafluorophosphate]. In the dry film, unconjugated, mono- and diconjugated, and strongly protein-linked (delta) bilirubin all react with the diazonium salt to produce azo dyes having absorption maxima at about 520 nm. With reflection densitometry and appropriate mathematical transformation, readings and bilirubin concentrations are linearly related to 260 mg/L. Results correlate well with those by the Jendrassik-Grof (Doumas modification) method (slope 0.994, intercept 1.1, correlation coefficient 0.993, Sy X x 4.0), and the method is precise (CV = 10.0% at Cav = 4.1 mg/L, 2.7% at Cav = 24.5 mg/L, 1.2% at Cav = 102 mg/L for patients' samples) and relatively free of interferences.
Time-resolved fluorometer for lanthanide chelates--a new generation of nonisotopic immunoassays.
Authors: Soini E , Kojola H 
Published: January 2020

Abstract
Pulsed-light time-resolved fluorometry of lanthanide chelates has proved to be very sensitive for use with nonisotopic immunoassays. We describe a manually operated fluorometer with a conventional xenon flashtube. Sensitivity for 1-s determinations is similar to that of radioisotopic methods.
Hormones in saliva: mode of entry and consequent implications for clinical interpretation.
Authors: Vining R F , McGinley R A , Symons R G 
Published: January 2020

Abstract
Assay of hormones in saliva would be more convenient than assay in blood, but there is no information on the route by which hormones enter saliva, information that would provide insight into the clinical value of such assays. We have examined the mode of entry of various hormones into saliva. The results suggest that unconjugated steroids enter saliva by diffusing through the cells of the salivary glands and that their concentration in saliva does not depend on the rate of saliva production. Conjugated steroids enter saliva via "ultrafiltration" through the tight junctions between the acinar cells, and their concentration in saliva is highly flow-rate dependent. Thyroxin and choriogonadotropin enter saliva via the ultrafiltration route or by contamination of the saliva by plasma or gingival fluid. We conclude that the salivary concentration of unconjugated steroids may usefully reflect the concentration of free (nonprotein-bound) steroids in plasma. Conversely, the concentration of conjugated steroids, thyroxin, and protein hormones such as choriogonadotropin in saliva probably does not reflect their concentration in plasma in any clinically useful way.
Liquid-chromatographic assay and identification of mono- and diester conjugates of bilirubin in normal serum.
Authors: Muraca M , Blanckaert N 
Published: January 2020

Abstract
This liquid-chromatographic procedure for determining bilirubin mono- and diester conjugates in normal serum is based on pre-analysis conversion of bilirubin monosugar and disugar conjugates to the corresponding methyl esters by alkaline methanolysis. Here, extracted unconjugated bilirubin, bilirubin monomethyl esters, bilirubin dimethyl ester, and internal standard are separated on a reversed-phase column within 15 min, detected in the effluent at 436 nm, and quantified from their peak areas. Carotenoids do not interfere. Within-day and day-to-day CVs range from 5 to 13%. The smallest concentrations of monoconjugated and diconjugated pigments that are detectable and measurable are about 10 and 20 nmol/L, respectively. Such data are given for sera from 43 healthy adults. Total bilirubin concentrations in serum tended to be lower in women than in men, but the relative amounts of the various bilirubin fractions in sera from men and women were comparable. Analysis of ethyl anthranilate azoderivatives from serum permitted identification of the bilirubin ester conjugates in normal serum as bilirubin 1-O-acyl glucuronides.