bluuebunny/crossref_metadata_2025 huggingface dataset:
Radioimmunoassay of calcitonin in the plasma of rhesus monkey and man.
Authors: Hargis G K , Reynolds W A , Williams G A , Kawahara W , Jackson B , Bowser E N , Pitkin R M
Published: January 2020

We describe a radioimmunoassay for rhesus monkey and human immunoreactive calcitonin, in which a selected goat anti-human calcitonin antiserum, 131I-labeled synthetic human calcitonin tracer, and purified synthetic human calcitonin standards were used. The mean basal concentration of calcitonin in normal monkey plasma (254 microgram/liter) was not significantly different from that in normal human plasma (217 microgram/liter). The data indicate that the method is sensitive (lower limit of detection, 5 ng/liter), specific, accurate, and reproducible (coefficient of variation, 1-11% over a wide range of concentrations). Monkey calcitonin response to changes in plasma calcium concentration is similar to that in man, with significant correlation between calcium and calcitonin concentrations. Use of this radioimmunoassay for monkey and human calcitonin allows the monkey to be used in further studies of factors regulating secretion, function, and metabolism of calcitonin under various experimental conditions that would not be feasible in man.
Serum estradiol-17 beta as determined by mass fragmentography and by radioimmunoassay.
Authors: Zamecnik J , Armstrong D T , Green K
Published: January 2020

We describe the preparation of [2,4,16,16-2H4]estradiol-17 beta. The method for quantitative determination of subpicomole amounts of estradiol-17 beta (trimethylsilyl ether derivatives) by gas-liquid chromatography-mass spectrometry with multiple ion detector and with [2H4]estradiol-17 beta as the carrier is presented and characterized. Values for serum samples, as measured by radioimmunoassay and by mass fragmentography, agreed well.
Evaluation of an aqueous fluorometric continuous-flow method for measurement of total urinary estrogens.
Authors: Hammond J E , Phillips J C , Savory J
Published: January 2020

Measurement of urinary estrogen excretion is used extensively to monitor fetal welfare in utero, allowing the fetus at risk to be identified. We evaluated a direct all-aqueous fluorometric method adapted to a continous-flow (AutoAnalyzer I) system, using a spectrofluorophotometer for detection. In this method, which is based on a modified Kober reaction, NaBH4 is used to eliminate the known negative interference of glucose. The mean analytical recovery was 98%. Urines from 15 men showed no blank fluorescence. Comparison studies of the fluorometric method (x) and a manual method based on the Kober/Ittrich reaction (y) yielded the equation y = 1.53x + 4.38 (r = 0.9235). The incomplete correlation can be explained by erratic extraction in the manual Kober/Ittrich procedure (mean recoveries were 57%). A day-to-day precision (CV) of 5.2% can be achieved with the automated method. Samples are analyzed at a rate of 20 per hour, but this rate can be doubled, if necessary, without significant carryover problems. We conclude that the automated fluorometric method is accurate, precise, and inexpensive and therefore the method of choice for measuring urinary estrogens.
Albumin activation of urinary amylase as determined with the Du Pont aca.
Authors: Garber C C , Carey R N
Published: January 2020

Protein activation of urinary alpha-amylase (EC 3.2.1.1) activity was observed during an evaluation of the Du Pont aca procedure for the determination of urinary alpha-amylase. This activation effect became constant for urinary albumin concentrations exceeding 1.50 g/liter. It is recommended that urinary alpha-amylase be analyzed with sufficient albumin added to maximize this effect. The aca alpha-amylase procedure is compared to an amyloclastic method for both serum and urine analysis. Expected ranges are presented for the aca method for serum and urinary amylase, amylase clearance, and the amylase clearance/creatinine clearance ratio.
Screening for urinary oligosaccharides: application to a mentally handicapped population and to patients with some other diseases.
Authors: Purkiss P , Hughes R C , Watts R W
Published: January 2020

The method for screening urinary oligosaccharides described in the accompanying paper [Clin. Chem. 24, 669 (1978)] has been applied to a large group of mentally handicapped patients as well as to patients with cystic fibrosis, malignant disease, and schizophrenia. The cause of the mental handicap was unknown in most cases. The primary object of the study was to investigate a possible link between some diseases and urinary complex carbohydrates. Our results show that abnormalities that are detectable in this way do not contribute significantly to the overall incidence of mental handicap, nor are they expressed in the other diseases studied.
Bis(2-ethylhexyl)phthalate concentrations in the serum of hemodialysis patients.
Authors: Lewis L M , Flechtner T W , Kerkay J , Pearson K H , Nakamoto S
Published: January 2020

Bis(2-ethylhexyl) phthalate is extracted from artificial kidneys, both in vivo and in vitro. Perfusion of whole blood through arterial-,venous tubing (that supplied with the dialyzer) for 1 h in vitro yielded 3.23 mg of the compound, while similar perfusion of the tubing plus the artificial kidney yielded 6.10 mg. Its mean concentration after dialysis in patients undergoing hemodialysis was 751 microgram/liter of serum. Patients who had undergone more than 50 hemodialysis treatments showed significantly higher postdialysis concentrations than patients who had undergone fewer. Uptake of bis(2-ethylhexyl) phthalate by the blood during a dialysis session followed two patterns. One set of patients showed a maximum concentration at 3 h, the second set showed a steady increase until the end of dialysis. Bis(2-ethylhexyl) phthalate appeared to be rapidly cleared from blood, most being removed within 5 to 7 h of completion of dialysis.
Urinary polyamine excretion during the menstrual cycle.
Authors: Osterberg S , Rosén S , Heby O
Published: January 2020

Urinary polyamines were measured by a fluorometric thin-layer chromatographic technique in samples collected daily throughout a single menstrual cycle by each of 13 healthy women. Polyamine excretion fluctuated considerably, but excretion of putrescine, spermidine, and spermine combined was consistently greatest during menstruation, sometimes extending into the early follicular phase of the cycle. Enhanced excretion of polyamines was also noticed in many individuals at the approximate time of ovulation.
A stable blood product for pH-blood-gas quality control.
Authors: Steiner M C , Shapiro B A , Kavanaugh J , Walton J R , Johnson W
Published: January 2020

We describe how to prepare, store, and use a hemolyzed blood product for simultaneous pH, pCO2, and pO2 quality control. Tonometry of the blood product with two oxygen and two carbon dioxide concentrations resulted in consistent and reproducible values during 38 weeks. The resulting pH values were consistent and reproducible, demonstrating the metabolic acid-base stability of the blood product. We conclude that the proper preparation, storage, and use of the product results in consistent, reproducible, and economical quality control for pH, pCO2 and pO2 blood measurements.
Improved iodination of peptides for radioimmunoassay and membrane radioreceptor assay.
Authors: Heber D , Odell W D , Schedewie H , Wolfsen A R
Published: January 2020

Generally applicable methods for iodinating and purifying small peptide radiolabels for radioimmunoassay and membrane radioreceptor are described in detail. Resulting improvements in radioreceptor assay and radioimmunoassay, as well as results of analyses of specific activity, separation from unlabeled peptide, and storage characteristics, are presented for luliberin, corticotropin, melanotropin, and calcitonin.
Evaluation of the JET technique for extracting drugs from urine.
Authors: Lantz R K , Eisenberg R B
Published: January 2020

A rapid extraction method preliminary to analysis for drugs in urine is described. Extraction columns containing purified cotton fiber (JETUBE, Manhattan Instrument Co., Santa Monica, Calif.) are shown to give high (approximately 90-97%) extraction efficiencies for some commonly prescribed or abused drugs, notably phenobarbital, amphetamine, morphine, and methadone. Analysis time, extraction efficiency, convenience, and eluate purity with a modified JET procedure are shown to be superior to results obtained with XAD-2 resin columns.
Multi-laboratory comparison of three heparin-Mn2+ precipitation procedures for estimating cholesterol in high-density lipoprotein.
Authors: Albers J J , Warnick G R , Wiebe D , King P , Steiner P , Smith L , Breckenridge C , Chow A , Kuba K , Weidman S , Arnett H , Wood P , Shlagenhaft A
Published: January 2020

Plasma high-density lipoprotein is commonly estimated by measuring the cholesterol remaining in plasma supernatant solutions after other lipoproteins, which contain apolipoprotein B, are precipitated with heparin and Mn2+. The method (method I) now in use by the Lipid Research Clinics, in which Mn2+ is at 46 mmol/liter final concentration, is reasonably accurate, but precipitation and sedimentation of lipoproteins other than high-density lipoproteins is often incomplete. We evaluated two modifications of method I. In method II, the Mn2+ concentration was doubled; the second modification (method III) included the increased Mn2+ concentration in a combined heparin Mn2+ reagent, decreased sample volume (2 ml), and a shorter incubation time (10 min at room temperature). The percentages of samples with turbid supernates (i.e., incomplete sedimentation) by methods I, II, and III were 9, 3, and 2%, respectively. Among non-turbid supernates, the percentages of samples containing measurable apolipoprotein B (incomplete precipitation) were 79, 19, and 16%, respectively. We conclude that method III is the most convenient and accurate of the three procedures.
Interlaboratory comparisons of nickel analyses in urine by atomic absorption spectrometry.
Authors: Adams D B , Brown S S , Sunderman F W , Zachariasen H
Published: January 2020

Two interlaboratory surveys of urine nickel analyses were performed in which eight or nine urine samples were distributed to laboratories in seven nations for measurements of nickel concentrations by atomic absorption spectrometry. In both surveys, wide discrepancies were observed in the values for urine nickel concentrations that were obtained in different laboratories by various analytical methods. This finding documents a serious need for improvement in the proficiency of nickel analyses. Nonetheless, excellent interlaboratory concordance was found in the rankings of urine samples in order of increasing nickel concentrations. Analytical techniques that involved preliminary wet or dry ashing and extration steps before flameless atomic absorption spectrometry were generally superior to techniques for direct analysis of urine by flameless atomic absorption spectrometry in respect to (a) analytical sensitivity, (b) recovery of added nickel, (c) interlaboratory precision, and (d) interlaboratory concordance of ranking of urine samples in order of increasing nickel concentrations.
Analysis for carbamazepine in serum by electron-capture gas chromatography.
Authors: Schwertner H A , Hamilton H E , Wallace J E
Published: January 2020

We describe an analytical method for determining carbamazepine in serum by electron-capture gas chromatography. A single-step extraction is followed by formation of the N-pentafluorobenzamide derivative with pentafluorobenzoyl chloride. For quantitation either of two internal standards may be used: 10-methoxy carbamazepine or 7-chloro-5,11-dihydrodibenz[b,e] [1,4]-oxazepine-5-carboxamide (Squibb Compound No. 10996). The procedure requires 0.5 ml of serum. Analytical recoveries are 96%. Coefficients of variation routinely are less than 2% for concentrations of carbamazepine that are within the therapeutic range.
Heparin--Mn2+ quantitation of high-density-lipoprotein cholesterol: an ultrafiltration procedure for lipemic samples.
Authors: Warnick G R , Albers J J
Published: January 2020

We describe a modified heparin--Mn2+ procedure for high-density-lipoprotein cholesterol quantitation, especially in lipemic samples. High-density-lipoproteins may be estimated as cholesterol remaining in plasma supernates after precipitation of other lipoproteins by heparin and Mn2+ treatment. However, in lipemic samples or those from non-fasting individuals, the lower density of the precipitated chylomicrons, very-low-, and low-density-lipoproteins frequently prevents their sedimentation by the usual low-speed centrifugation, and high-density-lipoprotein cholesterol thus is overestimated in the resulting turbid supernates. Sedimentation is improved by a twofold increase in Mn2+ concentration to 92 mmol/liter. The procedure reported here produced clear supernates in more than 95% of samples tested. Any remaining turbid supernates can be cleared by a simple, convenient ultrafiltration technique. The filtration removed essentially all of the very-low- and low-density-lipoproteins without removing appreciable amounts of high-density-lipoproteins.
Some problems in development of a high-performance liquid chromatographic assay to measure 25-hydroxyvitamin D2 and 25-hydroxyvitamin D3 simultaneously in human serum.
Authors: Stryd R P , Gilbertson T J
Published: January 2020

A high-performance liquid chromatographic technique was examined that may allow simultaneous measurement of 25-hydroxyvitamin D2 and 25-hydroxyvitamin D3 in a single sample of human serum. Concentrations of 4 microgram/liter or greater are accurately measured. However, the prepurification procedure allows partial separation of the two metabolites, and so tritiated 25-hydroxyvitamin D3 can be used as an internal standard for accurately monitoring the analytical recovery of 25-hydroxyvitamin D3, but not that of 25-hydroxyvitamin D2. The ability of most prepurification procedures to partly separate the 25-hydroxy metabolites of vitamin D2 and D3 mandates the need for individual internal standards to accurately monitor the recovery of each compound. Values obtained for 25-hydroxyvitamin D2 or composite 25-hydroxyvitamin D when only tritiated 25-hydroxyvitamin D3 is used as a means of monitoring recovery are probably in error.
Cholesterol in high-density lipoprotein: use of Mg2+/dextran sulfate in its enzymic measurement.
Authors: Finley P R , Schifman R B , Williams R J , Lichti D A
Published: January 2020

We describe a method for measuring high-density lipoprotein cholesterol. MgCl2 and dextran sulfate are used to precipitate all low-density and very-low-density lipoproteins. The supernate contains only high-density lipoproteins, the cholesterol concentration of which is estimated by an enzymic method, with a discrete analyzer (Abbott Bichromatic Analyzer). Concentration and instrument response are linearly related to 50 mg/liter. The precision of the method is excellent in the range of clinical interest (100 to 1000 mg of cholesterol per liter). The precision and efficiency of the precipitation are shown at various concentrations of high-density lipoprotein cholesterol. The method was compared to that of two laboratories in the Cooperative Lipoprotein Phenotyping Study group by testing a number of split samples, and agreement was good.
Inter-batch quality differences in purified human prolactin.
Authors: Fang V S , Armstrong J , Worsley I G
Published: January 2020

During the past four years, we secured six batches of purified human prolactin for iodination by the same lactoperoxidase technique. Two of these batches gave us more satisfactory results in terms of assay sensitivity and consistency than did the others, regardless of the antiserum used. Gel filtration of 125I-labeled hormone revealed that these two batches were composed of at least 55% "small" prolactin while the other four batches contained from 20 to 68% "big" prolactin. This qualitative difference was the most important contribution to assay discrepancies.
125I-radioimmunoassay for unconjugated estriol in serum of pregnant women.
Authors: Liedtke R J , Greaves J P , Batjer J D , Busby B
Published: January 2020

An 125I-radioimmunoassay is described which measures unconjugated estriol in the serum of pregnant women. Estriol is extracted into ethyl acetate/hexane, an aliquot is evaporated, and the residue is redissolved in phosphate buffer. The sample is incubated with tracer and antibody at 37 degrees C for 15 min and then at 4 degrees C for 1 h and 45 min. The antibody-bound fraction is then precipitated with polyethylene glycol and isolated by centrifugation. Because the antigen-antibody complex is stable in the presence of polyethylene glycol, the separation steps are not influenced by timing. Extraction recovery of 3H-labeled estriol added to a pool of sera from pregnant women averaged 96.7% (SD = 1.3, n = 10). Estriol-supplemented (5, 10, and 20 microgram/liter) serum from men, carried through the entire procedure, showed analytical recovery ranging from 94 to 106%. Structurally analogous steroids normally present in serum of pregnant women exhibit negligible cross reactivity. Day-to-day precision (CV) is 13.3% (3.1 microgram/liter), 6.4% (7.6 microgram/liter), and 5.6% (21.4 microgram/liter) for n = 21. The current reagent cost (about 17 cents per tube), and a total procedural time, including counting, of 5.5 h make this an acceptable assay for routine use.
Continuous-flow determination of bile acids in serum, and its clinical application.
Authors: Mashige F , Osuga T , Tanaka N , Imai K , Yamanaka M
Published: January 2020

We describe a highly sensitive and accurate automated continuous-flow method for determining bile acids in serum. The bile acids are first liberated from serum protein by dialysis at alkaline pH and then measured fluorometrically after the following enzymic reaction. Bile acids are converted to 3-oxo bile acids with 3alpha-hydroxysteroid dehydrogenase (EC 1.1.1.50) with concomitant reduction of NAD+ to NADH. The hydrogen in the generated NADH is transferred by diaphorase (EC 1.6.4.3) to resazurin to yield resorfin, the fluorophore. Only 100 microliter of serum is required and 40 determinations can be done per hour. The CV for 20 replicate determinations in serum with a mean bile acid concentration of 9.8 mumol/liter was 2.6%. The CV for day-to-day variation for another serum on 27 successive days was 3.0% (mean concentration, 10.0 mumol/liter). We applied this method to 826 sera from various diseases; 29% exceeded the upper limit of normal, 10 mumol/liter, and abnormally high values (greater than 20 mumol/liter) were almost exclusively limited to sera from hepatobiliary and enteric disorders.
Excretion of X-prolyl dipeptidyl-aminopeptidase in human urine as determined with a new fluorogenic substrate.
Authors: Kato T , Hama T , Kojima K , Nagatsu T , Sakakibara S
Published: January 2020

X-Prolyl dipeptidyl-aminopeptidase activity was found in human urine by a sensitive fluorescence assay in which a new fluorogenic substrate, 7-glycylproline-4-methylcoumarinamide, is used. The Km value was 2.9 X 10(-4) mol/liter, and the optimum pH was 8.7 in glycine-NaOH buffer. The enzyme activity was stable at 4 degrees C for at least five days. On Sephadex G-200 column chromatography, normal human urine showed a main peak with an approximate relative molecular mass of 400 000. The procedure is simple, rapid, and accurate. The enzyme activity in urine of normal adults was: 4.30 +/- 0.13 (SE) (range, approximately 1.84-8.96) micronmol/min per gram of creatinine, and 2.16 +/- 0.09 (SE) (range, approximately 0.38-6.98) micronmol/min per liter of urine.
A useful method for predicting creatinine clearance in children.
Authors: Shull B C , Haughey D , Koup J R , Baliah T , Li P K
Published: January 2020

A practical method for predicting creatinine clearance for pediatric patients from serum creatinine concentration and patient age is presented. Creatinine excretion rate (ER) can be predicted from the patient's age, in years, by the formula: ER = (0.035 X age) + 0.236. Using the predicted excretion rate and serum creatinine concentration, creatinine clearance can be predicted. There was good correlation (r = 0.90) between predicted and observed creatinine clearances in 101 subjects with various degrees of renal impairment. This method allows renal function to be rapidly estimated.
Improved continuous-flow (SMAC) determination of serum albumin.
Authors: Cederblad G , Hickey B E , Hollender A , Akerlund G
Published: January 2020

The albumin values determined by the bromcresol green methods do not compare well with values by more specific methods for albumin determination. The discrepancies have been related to, among other things, acute-phase reactants and are especially pronounced in the lower albumin range. These disadvantages are also inherent in a routine continuous-flow method for albumin (SMAC). The bromcresol green method has been improved considerably by shortening the reaction time before the absorbance is measured, as is described here. The modified method yields values that better agree with those by more specific methods and an influence of acute-phase reactants is no longer observed.
Continuous-Flow Determination of Dialyzable Calcium in Serum
Authors: Toffaletti John , Savory John , Gitelman Hillel J
Published: January 2020

Volume 23

p 1259, column 1, line 12: "0.50 mmol" should read "0.05 mmol."

Volume 24

p 264, column 1, top paragraph: a minus sign should be inserted in each of the two equations:

See Equations in the PDF File

p 270, column 1, line 11: "Figure 5" should read "Figure 3." In Table 1, the first column of numbers (3, 3, 4, 4, etc.) should be under the heading Binding capacity, %.

p 354: The last word should be deleted from the title of this paper.

p 518, column 3, second full paragraph: The third sentence should read "The dehydrofolate substrate, kept on ice, is 2 x 10-3 mol/liter in pH 6.0 phosphate buffer containing beta-mercaptoethanol." This author's present address is 1704 Francisco St., Berkeley, Calif. 94703.
Quantitative ultramicro-scale immunoenzymic method for measuring Ig antigenic determinants in single cells.
Authors: Hösli P , Avrameas S , Ullmann A , Vogt E , Rodrigot M
Published: January 2020

The Fluoro Ultra Micro Enzyme Linked Immuno Assay (FUMELIA) allows one routinely and quantitatively to measure a few thousand antigenic determinants on single cells. Highly purified Escherichia coli beta-galactosidase has been coupled to specific antibodies. By use of the Parafilm microcuvette techniuqe, the activity of the antibody-conjugated beta-galactosidase is assayed with a conventional spectrophotofluorometer. Attempts were undertaken to sensitize FUMELIA even further, so as to be able to detect a very few antigenic sites. It seems that even in its present state of development FUMELIA is more sensitive for the quantitation of cell-associated antigens than are techniques in which radiolabeled reagents are used. The potential of FUMELIA is illustrated by the quantitative measurement of membrane-bound immunoglobulins on single lymphocytes. It could be shown that T-cells as well as C-cells can synthesize Ig antigenic determinants. Thus it seems likely that T-cell receptors will, after all, be found to be immunoglobulins.
Prospective applications of calorimetry in the clinical laboratory.
Authors: Rehak N N , Young D S
Published: January 2020

Calorimetric analysis depends on the direct proportionality between the heat changes that occur during chemical reactions and the amount of reacting substances. Potential uses of calorimetry in the clinical laboratory are discussed, with examples. The calorimetric technique does not require optically clear specimens, and if the specificity of the measured reaction is assured, calorimetry can be used for quantitative determinations of components that are present in a complex matrix system such as body fluids. Specific enzymic reactions have been used to measure substrates and enzyme activities in biological specimens calorimetrically, with precision, sensitivity, and accuracy comparable to routine photometric techniques. The application of calorimetry in the clinical laboratory is limited now by its slowness, but development of automated instruments may enable the technique to become competitive with conventional analytical techniques in the clinical laboratory.
Adrenal status assessed by direct radioimmunoassay of cortisol in whole saliva or parotid saliva.
Authors: Walker R F , Riad-Fahmy D , Read G F
Published: January 2020

We describe a direct radioimmunoassay for cortisol in 10-microliter volumes of parotid saliva or whole saliva. Binding proteins are absent from these fluids, as demonstrated by the excellent correlation between results for samples assayed directly and by a comparison procedure involving extraction with 1,2-dichloroethane. The direct assay is specific, precise, and had a lower limit of sensitivity of 4 pg per assay tube. Comparison of cortisol concentrations in plasma, parotid saliva, and whole saliva in persons undergoing investigations for assessing adrenal function, including stimulation with cosyntropin (Synacthen) and suppression with dexamethasone, indicated that changes in plasma cortisol concentration were accurately and immediately reflected in saliva from either the parotidgland or whole saliva. A marked circadian rhythm has also been demonstrated for cortisol in parotid-gland saliva and whole saliva. We had to modify the 1,2-dichloroethane extraction procedure for accurate determination of cortisol in parotid saliva and whole saliva of patients undergoing treatment with metyrapone.
Determination of aluminum in biological samples by atomic absorption spectrophotometry with a graphite furnace.
Authors: Gorsky J E , Dietz A A
Published: January 2020

Aluminum, generally considered non-essential and non-toxic, may accumulate in toxic amounts in the brain in cases of chronic renal failure. We describe a procedure for its analysis in biological fluids by atomic absorption spectrophotometry with a graphite furnace. No sample preparation is required and the procedure is sensitive at the appropriate concentrations. A sample of serum or urine is pipetted into the interior of the graphite tube, where it is sequentially dried, charred, and atomized. Precautions for sample handling are discussed and instrument settings are defined. Precision and accuracy of the method are evaluated, as are the effects of salts, protein content of serum, and specific gravity of urine. Serum of 23 persons who were not consuming aluminum-containing antacids contained 28 +/- 9 (SD) microgram of Al per liter (1.02 +/- 0.33 mumol/liter).
Fluorometric determination of erythrocyte protoporphyrin in blood, a comparison between direct (hematofluorometric) and indirect (extraction) methods.
Authors: Peter F , Growcock G , Strunc G
Published: January 2020

We measured the concentration of erythrocyte protoporphyrin in 43 blood samples by two fluorometric methods. In the indirect method, protoporphyrin was extracted from blood and the fluorescence of the free acid in the extract was determined with a filter-fluorometer. These results were compared with results of direct determination of protoporphyrin in the same samples. In the direct assay the fluorescence of protoporphyrin, present in blood as the zinc salt, was measured without extraction, with the use of a hematofluorometer. Comparison of the results of the direct and indirect methods showed an excellent correlation (r = 0.986), but the hematofluorometric values (y) were approximately 9% lower than the fluorometric values (y = 0.911x). The slope of the regression line (0.911) is likely to be different for each hematofluorometer-fluorometer combination. Therefore, hematofluorometric values can only be compared with fluorometric values if the slope of the regression line is known and is used as a correction factor.
Clinical analysis of tamoxifen, an anti-neoplastic agent, in plasma.
Authors: Mendenhall D W , Kobayashi H , Shih F M , Sternson L A , Higuchi T , Fabian C
Published: January 2020

Tamoxifen, a phenylstilbene derivative, is currently being used to treat metastatic breast cancer. We describe an analytical method for monitoring the parent drug and its 4-hydroxylated derivative in whole blood and plasma. After extraction from biological media, the analytes are converted to highly fluorescent products by ultraviolet irradiation, and then separated by liquid-chromatography on a muBondapak CN column, with spectrofluorometric detection of components. Detection limits for tamoxifen and its 4-hydroxy derivative are 1 and 2 microgram/liter of biological fluid, respectively. Conditions have been optimized so that the reaction proceeds fast enough for convenient sample handling without jeopardizing fluorescence yield due to the photocatalyzed degradation of the fluorescent product. Evidence suggests that the fluorophore being monitored is a phenanthrene derivative.
Direct non-chromatographic radioimmunoassay of aldosterone: validation of a commercially available kit and observations on age-related changes in concentrations in plasma.
Authors: Tan S Y , Noth R , Mulrow P J
Published: January 2020

Human plasma aldosterone can be rapidly, directly, and reliably measured by radioimmunoassay with use of a commercially available anti-aldosterone antibody. With this method, we show that values tend to decrease with advancing age, especially after the sixth decade.
New continuous-flow analysis for simultaneous determination of creatinine and uric acid in 200 microliters of serum without use of a dialyzer.
Authors: Lolekha P H , Chantarothipol V , Wongvibulsin A
Published: January 2020

We present a new method for direct continuous-flow (AutoAnalyzer II) measurement of serum creatinine and uric acid. The manifold is simple, inexpensive, and can be constructed in the laboratory. Only 200 microliters of serum is needed; analysis rate is 60 samples per hour. The incorporation of sodium dodecyl sulfate and the simultaneous provision of blank subtraction make it possible to omit the dialysis step. Our method does not require the linearizer, since instrument response and concentration of creatinine and uric acid are linearly related to 200 and 120 mg/liter, respectively. The percentages of steady state, interaction, and recovery are acceptable, Precision is excellent and the results obtained from the new method correlate well with those obtained by the comparison methods. Interferences are few and, when encountered, are generally smaller than in the modified Technicon method. Marked hemolysis interferes only with the uric acid assay; marked turbidity has no effect on results for creatinine. Icteric serum with total bilirubin of 50 and 100 mg/liter interferes significantly with results for creatinine and uric acid, respectively, by the new method.
Direct solid-phase 125I radioimmunoassay of serum cortisol.
Authors: Brock P , Eldred E W , Woiszwillo J E , Doran M , Schoemaker H J
Published: January 2020

We report a solid-phase iodine- 125 radioimmunoassay for serum cortisol in which the interfering binding proteins are inactivated by a combination of reaction pH and 8-anilino-1-naphthalenesulfonic acid. The procedure is easy to perform and gives accurate and reliable results. The shift in pH for optimum binding of an antibody resulting from immobilization on a solid support, used to decrease cortisol binding competition in the present test, is potentially exploitable in other antibody and enzyme systems.
Measurement of chloroprocaine and procaine in plasma by flame ionization gas-liquid chromatography.
Authors: Smith R H , Brewster M A , MacDonald J A , Thompson D S
Published: January 2020

We describe an isothermal gas-liquid chromatographic procedure developed for measuring procaine and chloroprocaine in plasma. The unchanged drug is extracted into toluene from alkalinized plasma, together with an internal standard. The solvent is removed, the residue redissolved in methanol, and aliquots are injected into a 91.5-cm gas-liquid chromatographic column containing 3% OV-210. Sensitivity of detection is in the nanogram range.
Semi-automated micro-scale extraction apparatus for assay of free fatty acids in plasma.
Authors: Schade D S , Burke G , Eaton R P , DeMoss J
Published: January 2020

We describe the use of a semi-automated micro-scale extraction apparatus as applied to the assay of free fatty acids in plasma. With it, a smaller plasma sample is required, disposable glassware can replace acid-washed glassware, and the number of samples that one technican can assay per day is increased fivefold. Theroretically, this apparatus can be applied to all assay procedures requiring one or more extraction steps.
Enzymic serum cholesterol measurement with a basic autoanalyzer and Du Pont aca method.
Authors: Fingerhut B
Published: January 2020

I compared enzymic methods for total serum cholesterol as used with discrete (Du Pont aca and reagent packs) and continuous-flow (Boehringer Mannheim reagents and the Technicon AuotAnalyzer I) analysis of normal, icteric, and lipemic sera. The regression equation for 24 clear, non-icteric sera was: y (continuous flow) = 0.944x (aca) + 10.69; r = 0.971, Syx +/- 53.7 mg of cholesterol per liter. The continuous-flow system indicated no significant interference when as much as 350 mg of bilirubin was added per liter. Results with the aca method indicated a decrease in apparent cholesterol of about 5 mg/liter per milligram of added bilirubin. Serial diluting of lipemic sera resulted in falsely higher values with the aca method but no clinically significant effect on results with the AutoAnalyzer procedure. Apparent cholesterol as measured with the aca became proportionately greater than AutoAnalyzer values with increasing serum triglyceride concentration.
Emergency gas-chromatographic assay of phenobarbital and phenytoin and liquid-chromatographic assay of theophylline.
Authors: Shihabi Z K
Published: January 2020

Phenobarbital and phenytoin are extracted and concentrated in a single step, without solvent evaporation, followed by on-column methylation and gas-chromatographic quanitation. A similar extraction step for the assay of theophylline by high-pressure liquid chromatography is described. The extraction step can be completed in less than 2 min, the chromatographic step in less than 8 min. This extraction method yields clean chromatograms, avoids evaporating health-hazardous solvents, and is applicable to other drugs.
Interaction between human IgG and human creatine kinase isoenzyme-1 in serum: a route for the intravascular catabolism of creatine kinase-1?
Authors: Prabhakaran V , Nealon D A , Henderson A R
Published: January 2020

In vitro incubation, at 37 degrees C, of human creatine kinase isoenzyme-1 (isoenzyme BB) and human immunoglobulin G in a buffer results in the formation of a complex of high relative molecular mass (Mr approximately 825,000), which contains both proteins. This complex also forms in vitro if creatine kinase isoenzyme-1 is incubated with fresh human serum. The creatine kinase activity of the complex obtained from either incubation is extremely labile, even in the presence of a chelating agent and a thioglycerol. We present evidence for the existence of this complex in the sera of patients who have detectable serum creatine kinase isoenzyme-1 activity. Sera with high activities of creatine kinase isoenzyme-2 do not appear to have this complex. We therefore speculate that complexing of creatine kinase isoenzyme-1 with serum immunoglobulin G may be a pathway of enzyme degradation.
Aqueous primary standard for use in measuring cholesterol by the cholesterol oxidase method.
Authors: Abele J , Khayam-Bashi H
Published: January 2020

An aqueous primary standard is needed for measuring cholesterol by enzymatic procedures. Sodium deoxycholate solubilizes cholesterol in water. Crystalline cholesterol (1.00, 3.00, 4.00, and 5.00 g/L), added to a solution containing 150 g of this compound per liter of a 9 g/L saline solution, was measured by a cholesterol oxidase procedure, with a centrifugal analyzer. The solubilizer did not interfere. When compared to an isopropanol-based commercial cholesterol standard, the cholesterol standard in solubilizer showed excellent correlation (r = 0.986; m = 0.989). Day-to-day variation for the mixture during nine days was small (CV, 2.9% at 100 g/L, 3.7% at 3.00 g/L, and 1.8% at 4.00 g/L). Linearity was maintained up to 5.00 g/L. The cholesterol concentration in four reference sera so analyzed maintained CV's of less than 4%. The viscosity of the mixture was similar to that of serum. The standard mixtures, stored at room temperature for 360 days, remained stable. The solubilized cholesterol standard is shown to be suitable for use in the enzymatic procedure.
Monitoring diazepam and desmethyldiazepam concentrations in plasma by gas-liquid chromatography, with use of a nitrogen-sensitive detector.
Authors: Dhar A K , Kutt H
Published: January 2020

We describe a modified [from Anal. Chem. 36, 2099 (1964)] procedure for determining diazepam and its pharmacologically active metabolite, desmethyldiazepam, in plasma, with use of a nitrogen-sensitive detector in the gas-liquid chromatography. We used medazepam as the internal reference standard. Diazepam and desmethyldiazepam are converted to their respective benzophenones by mineral acid hydrolysis. With this procedure, as little as 100 muL of plasma can be used to determine the drug in concentrations as low as 10 microgram/L, accurately, reproducibly, and quickly. Within-run and between-run CVs for 100 microgram/L concentrations of the two compounds were 5 and 7%, respectively.
Effects of Ca, Mg, and EDTA on creatine kinase activity in cerebrospinal fluid.
Authors: Urdal P , Strømme J H
Published: January 2020

For one to obtain a precise estimate of creatine kinase (CK) activity in cerebrospinal fluid, the sample fraction is increased by about 10-fold over that used for serum. This increases the concentration of interfering substances, Ca being especially important. Therefore, the relationship between Ca, Mg, and EDTA was examined. Enzyme activity was maximal with 15 mmol of Mg per liter in the presence of 3 mmol of EDTA per liter, otherwise according to the (Scandinavian) recommended conditions for determination of CK activity in serum. These modifications increased the activity of CK by 35% for CK-MM and by 60% for CK-BB. Counteraction of Ca-induced inhibition was the main reason to this increase. We describe a practical and sensitive method for determining CK in cerebrospinal fluid.
Evaluation of two commercially available laser nephelometers and their recommended methods for measurement of serum immunoglobulin G.
Authors: Walsh R L , Coles M E , Geary T D
Published: January 2020

The Hyland and Behring laser nephelometer systems for assay of specific proteins are described. Immunoglobulin G was measured to assess the overall performance of the two systems. Intra-batch precision figures were comparable to those for the radial immunodiffusion method run routinely in our laboratory. There was no significant interference from turbid or lipemic specimens. Accuracy, ease of instrument operation, standard curve stability, linearity, and accessory equipment are discussed. Immunoglobulin G is measured rapidly, accurately, and precisely by either system.
Immobilized enzymes in continuous-flow analysis.
Authors: Werner M , Mohrbacher R J , Riendeau C J , Murador E , Cambiaghi S
Published: January 2020

Glucose oxidase, uricase, and urease were immobilized on the interior surface of activated polyamide tubing. The shelf-life of such enzyme bearing tubes was at least six months. The tubes were used for continuous-flow analysis of glucose, uric acid, and urea with conventional systems and with hybrid micro-scale systems in which modules of different manufacture were combined. The length of enzyme-bearing tube required for each system was ascertained empirically. Each tube could be used for several thousand assays, but glucose oxidase-bearing tubes were more stable than urease- or uricase-bearing tubes. Results for patients' samples correlated well with results obtained by accepted methods.
Determination of amniotic fluid phospholipids by thin-layer chromatography, with use of a hydrogen flame ionization detector.
Authors: Martin-Ponthieu A , Porchet N , Fruchart J C , Sezille G , Dewailly P , Codaccioni X , Delecour M
Published: January 2020

We describe a new specific method for measuring lecithin, sphingomyelin, and phosphatidylglycerol in amniotic fluid by thin-layer chromatography, with use of a hydrogen flame ionization detector. After extraction and acetone precipitation to isolate surface-active lecithin, the phospholipids are separated on a thin rod of refractory and chemically stable material, having an outer coating of a bonded, sintered partition medium. Two solvent systems are used to develop the chromatograms, chloroform/methanol/water to separate lecithin and sphingomyelin, tetrahydrofuran/methylal/methanol for phosphatidylglycerol. Then the rod is passed through an hydrogen flame; the resulting ions produced generate a current, which is amplified and fed to a potentiometric recorder. The height of integral curves was proportional to the area under each peak. For quantitation we used an internal standard (lysolecithin in the first system. phosphatidyldimethylethanolamine in the second). The method requires less than 5 mL of amniotic fluid; results are available within 6 h.
Quantitation of urinary porphyrins by use of second-derivative spectroscopy.
Authors: Jones K G , Sweeney G D
Published: January 2020

We describe a simple, rapid procedure for measuring porphyrins in urine. After acidification of a urine specimen with hydrochloric acid, the second derivative of the absorption spectrum is recorded in the region of the Soret band maximum. The amplitude of the deflection is linearly related to porphyrin concentration, and the point at which the second derivative minimum occurs provides an estimate of the ratio of uroporphyrin to coproporphyrin in the sample. Nonspecific interference is not significant and reproducibility is excellent. Porphyrin excretion was studied in 24-h urine collections from men and non-pregnant as well as pregnant women. Median daily porphyrin excretion (nmol) was: men, 65.0; non-pregnant women, 60.1; and third-trimester pregnant women, 175.0. Distribution of these data was significantly skewed; upper and lower 2.5 percentile limits are given.
Enzyme immunoassay for human ferritin.
Authors: Watanabe N , Niitsu Y , Ohtsuka S , Koseki J , Kohgo Y , Urushizaki I , Kato K , Ishikawa E
Published: January 2020

We describe an enzyme immunoassay with use of beta-D-galactosidase for quantitation of ferritin in human serum. The minimum detectable ferritin concentration is 0.25 microgram/L of serum, which is comparable to results obtained by radioimmunoassay. The correlation coefficient between values determined by enzyme immunoassay and radioimmunoassay was 0.95 (n - 1 = 85, p less than 0.001).
Erythrocyte protoporphyrin/heme ratio in the assessment of iron status.
Authors: Labbé R F , Finch C A , Smith N J , Doan R N , Sood S K , Madan N
Published: January 2020

The protoporphyrinemia of iron deficiency is well recognized. Clinically, information on the protoporphyrin/heme molar ratio in whole blood offers certain advantages over protoporphyrin measurement alone. A procedure for determining this ratio is reported. Protoporphyrin is extracted, solubilized, and measured fluorometrically. Heme (as hemin chloride) is precipitated with the blood proteins, the precipitate is dissolved in an alkaline/pyridine solvent, and the resulting bispyridine ferriprotoporphyrin is measured spectrophotometrically. The molar ratio of these two metabolites correlates well with values for plasma ferritin, plasma iron, transferrin saturation, hemoglobin, and hematocrit. In some cases the ratio increases detectably while the other variables, especially hematocrit and hemoglobin, remain normal. Evidently it is a more sensitive index to iron status. For healthy men and women, the mean ratio is 16.0 (SD, 5.3). The mean + 3 SD, or a ratio of 32, is distinctly abnormal, as shown by a confirmatory test. We validated the test by surveying routine blood specimens obtained from several population groups.
Improved radioimmunoassay of urinary estriol.
Authors: Jawad M J , Wilson E A , Kincaid H L
Published: January 2020

We report a rapid double-antibody radioimmunoassay for urinary estriol. Advantages over other current methods include: (a) 30-min hydrolysis; (b) total incubation time, 55 min; (c) assay unaffected by urinary glucose; (d) no degradation of estriol evident during hydrolysis; (e) superior (85%) analytical recovery of estriol conjugates; (f) linear standard curve by logit-log extrapolation; (g) good correlation (r = 0.83) with total estrogen determination by a generally accepted colorimetric method; (h) only 20 muL of urine required; and (i) the detection range is 1.9 to 100.5 mg/24-h urine.
DuPont aca III performance as tested according to NCCLS guidelines.
Authors: Garber C C , Westgard J O , Milz L , Larson F C
Published: January 2020

We evaluated the analytical performance of 10 representative channels on the new microprocessor-controlled DuPont aca III according to the guidelines (draft documents PSEP-2, 3, and 4) proposed by the Instrument Evaluation Subcommittee of the National Committee for Clinical Laboratory Standards. These guidelines were used for the experimental design and data analysis for the precision and accuracy testing, the latter by comparison with an aca II, with results of atomic absorption spectroscopy for calcium, and with the National Glucose Reference Method. From a 20-day replication study, we estimated within-run, between-run/within-day, between-run/between-day, and total standard deviations at three concentrations for each method. From duplicate analyses of 100 samples on the aca III, aca II, and other methods, we estimated the bias from the regression line at specific concentrations and total error from a tolerance limit about the regression line. Analytical performance of the aca III was judged acceptable because these estimated errors were small.
Metabolic balance of aluminum studied in six men.
Authors: Gorsky J E , Dietz A A , Spencer H , Osis D
Published: January 2020

The metabolism of aluminum was followed in patients who were receiving strictly controlled diets, either unaltered or supplemented with aluminum-containing antacids. Aluminum was determined by atomic absorption spectrophotometry with a graphite furnace. All food, water, and medications were analyzed, as were aliquots of urine and stool collected throughout six-day periods. Patients were usually studied for five consecutive six-day periods on the same diet and aluminum intake. This study included six patients who were studied for seven to 21 such six-day periods. During control periods, when the patients were receiving less than 5 mg of aluminum per day, the balance was usually slightly negative, but when the diet was supplemented with antacids to contain 1--3 g of aluminum per day, an average positive balance of 23 to 313 mg of aluminum per day was observed for the total time on the same intake. Consecutive six-day periods while a subject was receiving antacids might show either positive or negative balances, but the average retention for 18--84 days on antacids was always positive. Thus the potential effects of the storage of aluminum in the tissues must be considered in the chronic administration of antacids.