bluuebunny/crossref_metadata_2025_split huggingface dataset:
Heparin--Mn2+ quantitation of high-density-lipoprotein cholesterol: an ultrafiltration procedure for lipemic samples.
Authors: Warnick G R , Albers J J 
Published: January 2020

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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.