bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fluorescence polarization immunoassay IV. Determination of phenytoin and phenobarbital in human serum and plasma.
Authors: Lu-Steffes M , Pittluck G W , Jolley M E , Panas H N , Olive D L , Wang C H , Nystrom D D , Keegan C L , Davis T P , Stroupe S D 
Published: January 2020

Abstract
Fluorescence polarization immunoassays for phenytoin and phenobarbital in human serum or plasma are described and shown to be clinically useful. No sample pretreatment, extraction, or phase separation is required. A determination can be made with less than 20 microL of sample in 15 min, with incubation at ambient temperature. Abnormal concentrations of protein, lipid, hemoglobin, or bilirubin do not interfere. In addition, drug metabolites and commonly co-administered drugs do not affect the assay results at clinically significant concentrations. Analytical recoveries of each of the two anticonvulsant drugs from serum averaged 101%. Between-assay CVs were less than 6.5%, with sensitivities of 0.5 mg/L. Comparison of this method with "high-performance" liquid chromatography, homogeneous enzyme immunoassay, and radioimmunoassay for phenytoin determinations yielded correlations of 0.99, 0.98, and 0.99, respectively. Similar comparison studies for phenobarbital yielded correlation coefficients of 0.99, 0.98, and 0.99, respectively.
Liquid-chromatographic measurement of phenylalanine and tyrosine in serum.
Authors: Spierto F W , Whitfield W , Apetz M , Hannon W H 
Published: January 2020

Abstract
With phenylalanine ammonia-lyase (EC 4.3.1.5) we converted phenylalanine (Phe) and tyrosine (Tyr) to transcinnamic acid and p-coumaric acid, respectively. These were separated by "high-performance" liquid chromatography and detected at 280 nm. We measured the Phe and Tyr content of human serum by adding 100 mU of the enzyme to a 20-microL serum aliquot, mixing for 2 h at 24 degrees C, then stopping the reaction with 1 mL of cold methanol. Precipitated proteins were removed by centrifugation and the separated clear supernates were stored at -20 degrees C. For chromatographic separation, detection, and quantification, we used a system equipped with a C-18 reversed-phase column, a variable-wavelength spectrophotometer, a printer-plotter, and a microcomputer. The mobile phase was a mixture of dilute aqueous (50 g/L) acetic acid and CH3CN (80/20, by vol). CVs for specimens containing 100 mg of Phe or Tyr per liter varied from 5 to 10%. Analytical recoveries were near 100%.
Pitfalls in the American Monitor kit methods for determination of total and "direct" bilirubin.
Authors: Doumas B T , Perry B W , Jendrzejczak B , Katona V 
Published: January 2020

Abstract
We evaluated the American Monitor Corporation kit for total and direct-reacting bilirubin and found that it suffers serious deficiencies, which lead to inaccurate and imprecise results. The main problem with the total-bilirubin procedure is that the short reaction time (2 min) is inadequate for completion of the reaction. The poor precision of the direct-bilirubin method is due to the short reaction time and the inability of the "stabilizer" (hydroxylamine sulfate) to completely destroy the diazo reagent. Depending on when Fehling's reagent is added, the reaction time may vary from 2 min to 7 min. Values for direct bilirubin at 7 min exceed those obtained at 2 min by 17 to 29%. The short reaction time makes color development temperature dependent, an additional source of imprecision. The suboptimal concentration of the diazo reagent results in underestimation of direct-reacting bilirubin. We recommend changes that improve both precision and accuracy of the kit procedures.
Kinetic method having a linear range for substrate concentrations that exceed Michaelis-Menten constants.
Authors: Hamilton S D , Pardue H L 
Published: January 2020

Abstract
We describe a new data-processing method for the kinetic quantification of substrates of enzyme-catalyzed reactions. Nonlinear regression is used to fit data for absorbance (A) and rate (dA/dt) vs time to the rate form of the Michaelis-Menten equation. Fitting parameters are the maximum velocity (Vmax), the Michaelis constant (Km), and the total absorbance change (delta A infinity) that would be observed if the reaction were monitored to completion. The method is evaluated with use of the uricase-catalyzed oxidation of uric acid, monitored at 293 nm, as a model reaction. Results for aqueous solutions demonstrate linear calibration plots for concentrations from well below to 3.5-fold the Michaelis constant, a zero temperature coefficient (36-38 degrees C), and near zero dependence on inhibitor (xanthine) concentrations that reduce the initial rate of 28% of its uninhibited value. Relative standard deviations (RSDs) vary from about 2 to 15%, depending on the data range (95-65% completion) used to process the data. For an 80% reaction data range, the pooled RSD was 6%. The sensitivity for uric acid is 1.15 x 10(4) L mol-1 cm-1 and the detection limit (95% confidence level) is 1.2 x 10(-6) mol/L.
Sodium measurements in multiple myeloma: two techniques compared.
Authors: Ladenson J H , Apple F S , Aguanno J J , Koch D D 
Published: January 2020

Abstract
Sodium was determined by flame photometry and by direct potentiometry in 56 serum or plasma samples from 24 patients with multiple myeloma or macroglobulinemia. We observed differences between the two techniques as large as 17 mmol/L (12%). The flame-photometric values decreased relative to the direct-potentiometric values as protein increased or water content decreased. Moreover, the two sodium measurements could not be interconverted simply on the basis of correcting for protein or water content. There was significantly lower residual variance (p less than 0.005) when the direct-potentiometric sodium values were compared with the osmolality (corrected for the influence of glucose and urea nitrogen) than when the flame-photometric values for sodium were so compared. We conclude that direct potentiometric measurements of sodium in patients with multiple myeloma gives clinically relevant results but flame photometry does not. Clearly, the method by which sodium is measured in patients with multiple myeloma must be considered if results are to be interpreted correctly.
Biliprotein in adult icteric serum--demonstrated by extension of the alkaline methanolysis procedure.
Authors: Wu T W , Sullivan S S 
Published: January 2020

Abstract
We confirmed that the alkaline methanolysis procedure of Blanckaert (Biochem. J. 185: 115-128, 1980) converts the sugar conjugates of bilirubin (Bc) into their corresponding methyl and dimethyl esters, which can be extracted into chloroform along with underivatized unconjugated bilirubin (Bu). By this procedure, we accounted for Bu nearly quantitatively, but only 76-83% of total Bc. By pretreating samples containing Bu and (or) Bc with a caffeine/benzoate reagent, we improved the analytical recovery of Bc to 85-93% without affecting the Bu. When the method (+ caffeine/benzoate) was applied to adult icteric serum, a variable fraction (20-75%) of the original total bilirubin (based on diazo reactivity) remained with the protein pellet, which is routinely discarded in the original methanolysis procedure. In this pellet we demonstrated the occurrence of a strongly protein-bonded bilirubin fraction (biliprotein) similar to the recently described "delta" fraction (Clin. Chem. 28: 629-637, 1982). The analytical and clinical implications of our findings are discussed.
Optimizing the o-phenylenediamine assay for horseradish peroxidase: effects of phosphate and pH, substrate and enzyme concentrations, and stopping reagents.
Authors: Bovaird J H , Ngo T T , Lenhoff H M 
Published: January 2020

Abstract
Horseradish peroxidase, assayed with o-phenylenediamine, is irreversibly inactivated when incubated in phosphate buffer, 100 mmol/L, at pH 5. The inactivation depends on both duration and incubation and phosphate concentration. Phosphate was the most potent inactivator and citrate the least potent of a series of buffers tested. The inactivation is not attributable to ionic strength per se or to Na+ or K+. The observed inactivation did not occur at high concentrations (2500 nmol/L, 0.1 g/L) of enzyme; however, this "protective" effect could not be reproduced by adding bovine serum albumin or a surfactant (Tween 20) to lower concentrations of enzyme. The inactivation was independent of commercial source of the enzyme or the kind of chromogenic assay used. On the basis of this information, we optimized the assay so that it gave eightfold greater absorbance values than those reported by others. The improved assay was sensitive to as little as 0.4 pmol/L (16 ng/L) of peroxidase, and was linear over the range of 0.4 to 5 pmol/L (16-200 ng/L).
ILIS--An integrated laboratory information system. I. Biochemistry and hematology.
Authors: Deshpande S U 
Published: January 2020

Abstract
IBM System 34 (central processing unit, 128 kilobytes; fixed disks, 128.4 megabytes) with seven cathode-ray tubes has been used by our clinical laboratories for the last 30 months. All data-entry programs are in a conversational mode, for on-line corrections of possible errors in patient identification and results. Daily reports are removed from the medical records after temporary and permanent cumulative weekly reports are received, which keep a three-month track of the results. The main advantages of the system are: (a) the increasing laboratory work load can be handled with the same staff; (b) the volume of the medical record files on the patients is decreased; (c) an easily retrievable large data base of results is formed for research purposes; (d) faster billing; and (e) the computer system is run without engaging any additional staff.
Creatine kinase isoenzymes in serum from cord blood and the blood of healthy full-term infants during the first three postnatal days.
Authors: Jedeikin R , Makela S K , Shennan A T , Rowe R D , Ellis G 
Published: January 2020

Abstract
Isoenzymes of creatine kinase (ATP:creatine phosphotransferase; EC 2.7.3.2; CK) were measured by electrophoresis in serum from cord blood and skin-puncture blood taken from 45 healthy full-term infants during the first three postnatal days. Mean total CK activities (in U/L at 30 degrees C) were 185 in cord samples, 536 in samples taken between 5--8 h postnatally, 494 between 24--33 h, and 288 in the 72-100 h samples. Values for all three isoenzymes increased to a peak over this period, with the highest values generally being found in the samples taken 5--33 h after birth; the subsequent decline was most rapid for CK-BB. Serum CK isoenzymes in cord samples and those taken at 72--100 h in the 11 babies delivered by cesarian section did not differ significantly from those of babies delivered vaginally. However the postnatal increases in total CK, CK-MM, and CK-MB (but not in CK-BB) were significantly greater in those patients born by vaginal delivery. The reasons for the increases in CK isoenzymes after birth are not clear, but our results and reported studies on the ontogeny of CK suggest that CK-MB cannot be regarded as a "cardiac-specific" isoenzyme in the neonatal period.
Interactions among enzyme, antibody, drug, and time in enzyme immunoassays for drugs of abuse.
Authors: Osterloh J , Butrimovitz G P 
Published: January 2020

Abstract
Published information on the major interactive variables of enzymic immunoassays for drugs, whether in urine or serum, is scanty. Using the Syva EMIT-dau Barbiturates assay as an example, we examined the following interactive variables with respect to test response: concentrations of enzyme, antibody, and drug; urine matrix; and time. The results suggest a process for optimizing this type of enzyme immunoassay. Transformation of the data gives indirect evidence of heterogeneous antibody reactions that are drug-concentration dependent.
Laboratory differentiation of hypercalcemic patients.
Authors: Johnson K R , Howarth A T , Hamilton M , Mascall G C 
Published: January 2020

Abstract
We studied the biochemical discrimination of primary hyperparathyroidism from other causes of hypercalcemia. This potentially serious disorder is readily remedied, and because recent work has suggested that even very mild cases in elderly people derive substantial benefit from surgery, the correct diagnosis is crucial. A discriminant function is derived that maximizes the use of data that are readily available from general hospital laboratory; application of the Hamilton "T score" system simplifies its interpretation. We conclude that the best use of this formula is as a negative discriminant, to identify some non-hyperparathyroid cause of hypercalcemia, and also as a partial positive discriminant, to identify some cases of primary hyperparathyroidism. We review previous such discriminants and consider the reasons why they have been less successful.
Improved procedure for lecithin/sphingomyelin ratio in amniotic fluid reduces false predictions of lung immaturity.
Authors: Brown L M , Duck-Chong C G , Hensley W J 
Published: January 2020

Abstract
Many laboratories have found that their procedure for determining lecithin/sphingomyelin (L/S)ratios gives an unacceptably high proportion of false predictions of fetal lung immaturity. We investigated each step in the procedure, in an attempt to improve the clinical performance of the test and to make the method more amenable to standardization between laboratories. L/S ratios were determined by the new procedure in amniotic fluid from 147 pregnancies, collected within two days of delivery of the infant. Four cases had an L/S ratio less than 2; all developed hyaline membrane disease. No other cases of hyaline membrane disease were encountered in this study. For 106 of these pregnancies, the L/S ratio was also determined by the procedure previously in use. This predicted lung immaturity for 16 infants, only four of whom developed hyaline membrane disease. All 12 cases incorrectly predicted as immature by the old procedure were correctly classified by the new procedure.
Methylene unit calibration for analysis of organic acids by gas--liquid chromatography/mass spectrometry.
Authors: Bromberg I L , Heininger J A , Cherian A G 
Published: January 2020

Abstract
We describe a method for automatic computation of "methylene unit" retention-time indices in real time on a computer-controlled gas chromatograph/mass spectrometer system. The calculation is based on the exponential relationship between the methylene unit values of hydrocarbon reference standards and the oven temperature at their elution. Using this mathematical relationship, we calculated calibration factors, which eliminates the need to include a set of methylene unit reference standards with each run and simplifies and speeds identification of unknown peaks in chromatograms. Long-term stability and good precision of the calibration factors were observed during the six-month period of study.
A variant alkaline phosphatase in renal cell carcinoma.
Authors: Whitaker K B , Eckland D , Hodgson H J , Saverymuttu S , Williams G , Moss D W 
Published: January 2020

Abstract
We report a case of renal cell carcinoma in which up to 32% of the abnormally increased alkaline phosphatase activity in serum was contributed by a variant alkaline phosphatase originating in the primary tumor and its secondary deposits. The variant enzyme was probably an altered form of normal renal alkaline phosphatase. The rest of the alkaline phosphatase activity in the serum was of hepatic origin, but no abnormality of the liver was discovered at autopsy.
Comparing multivariate and univariate subject-specific reference regions for blood constituents in healthy persons.
Authors: Harris E K , Yasaka T , Horton M R , Shakarji G 
Published: January 2020

Abstract
We examined the comparative behavior of subject-specific multivariate and univariate reference regions, using both computer-generated data and serial (semi-annual) measurements of selected analytes in subjects from a large health-maintenance program. Univariate studies under both homeostatic and random-walk time-series models were helpful in defining expected results, but only the homeostatic model was used in multivariate as well as univariate forms. Analysis of the computer-generated data and the real biochemical series produced similar findings, which showed the multivariate subject-specific reference region to be much more conservative than corresponding univariate intervals. That is, a multidimensional point of p correlated observations is quite likely to lie within the individual's multivariate reference region (based on past observation vectors), even when one or more of the observations lie outside their separate reference intervals for that individual. One consequence of this high specificity against univariate false positives in a large surveillance program is a higher than expected proportion of positive multivariate vectors in which none of the values lie outside their univariate ranges. Thus, although the development of multivariate reference regions should be encouraged, they should be used in conjunction with, not instead of, univariate ranges.
Multivariate and univariate optimization studies of liquid-chromatographic separation of steroid mixtures.
Authors: Fast D M , Culbreth P H , Sampson E J 
Published: January 2020

Abstract
We developed a high-performance liquid-chromatographic separation of five steroids (estriol, estradiol, cortisol, progesterone, and testosterone), eluting with a water-acetonitrile gradient from a reversed-phase (C18) column. By applying a simplex search algorithm to maximize a chromatographic-response function, we sought to optimize the original conditions of the chromatographic analysis, which did not separate two pairs of overlapping peaks. Our chromatographic-response function incorporated both peak separation and total time of analysis. Three factors were varied simultaneously to maximize this function: flow rate, column temperature, and gradient shape. From the simplex optimization, we selected a flow rate of 1.50 mL/min, a temperature of 52 degrees C, and a linear gradient for our analysis. Subsequent univariate studies of the initial mobile phase composition showed that acetonitrile/water (20/80 by vol) gave an adequate separation.
Quantitative liquid-chromatographic technique for the simultaneous assay of tricyclic antidepressant drugs in plasma or serum.
Authors: Sonsalla P K , Jennison T A , Finkle B S 
Published: January 2020

Abstract
A quantitative "high-pressure" liquid-chromatographic assay for tricyclic antidepressant drugs in plasma or serum is described in which amitriptyline, nortriptyline, imipramine, desipramine, doxepin, and desmethyldoxepin are separated with a 10-micrometer particle size silica column and a methanol/NH4OH/NH4NO3 solvent system. The drugs and two internal standards are extracted with hexane/isoamyl alcohol, the solvent layer is evaporated at 40 degrees C, and the drugs are detected at 254 nm. Drug concentrations are linear with absorbance from 25 to 1000 micrograms/L; within-assay and between-assay CVs are less than or equal to 10%.
Sample preparation and liquid-chromatographic analysis for tricyclic antidepressants in serum.
Authors: Koteel P , Mullins R E , Gadsden R H 
Published: January 2020

Abstract
We report two separate sample-preparation procedures and a "high-pressure" liquid-chromatographic method for quantitating nine tricyclic antidepressant drugs: trimipramine, doxepin, amitriptyline, imipramine, desmethyldoxepin, nortriptyline, desipramine, maprotiline, and protriptyline. The drugs are extracted from 1 mL of serum by a single manual hexane extraction or by using DuPont's PREP I Automated Sample Processor. The drugs from either process are chromatographed on a mu-Bondapak-CN column with a mobile phase of acetonitrile/methanol/Na2HPO4, 5 mmol/L (60/15/25 by vol), pH 7.0, at a flow rate of 2.0 mL/min. Absorbance at 254 nm is linear with drug concentration from 25 to 1000 mg/L for each drug. With the manual extraction procedure the detection limit was 10 mg/L, absolute recovery 20-44%, within-run precision (CV) 10.1%, and run-to-run precision 11.1%. The performance of automated sample extraction was better, with a detection limit of 5 mg/l, absolute recovery 72-97%, within-run precision 6.1%, and run-to-run precision 6.6%.
Two-dimensional electrophoretic analysis of human leukocyte proteins from patients with rheumatoid arthritis.
Authors: Willard K E , Thorsrud A K , Munthe E , Jellum E 
Published: January 2020

Abstract
Human leukocyte proteins from more than 150 patients with rheumatoid arthritis, together with age- and sex-matched controls, were analyzed by use of the ISO-DALT technique in two-dimensional polyacrylamide gel electrophoresis. Patients with ankylosing spondylitis, polymyalgia rheumatica, psoriatic arthritis, calcium tendinitis, post-infectious arthritis, and asymmetrical seronegative arthritis were also included as positive controls. Synthesis of several proteins, referred to by number as members of the "Rheuma" set, is shown to increase in the leukocyte preparations from patients with classical rheumatoid arthritis. Several of these proteins are specific to monocytes or granulocytes; others are of unknown cellular origin, but appear to be unique to rheumatoid arthritis. The Rheuma proteins appear to be indicators of disease activity, because their increased synthesis can be correlated with sedimentation rate and other clinical indices of rheumatoid disease activity.
A two-dimensional electrophoretic analysis of the heat-shock-induced proteins of human cells.
Authors: Anderson N L , Giometti C S , Gemmell M A , Nance S L , Anderson N G 
Published: January 2020

Abstract
Using two-dimensional electrophoresis, we have investigated the responses of human cells in culture to heat shock and to various chemical agents producing a similar effect. These treatments result in the induction of increased synthesis of several specific proteins. One (HShock:1, SDS-molecular mass about 65000) is increased by about 350-fold over the amount in untreated cells. Computer analysis of time-course studies indicates, however, that rates of synthesis of various proteins other than the classical "heat shock proteins" are affected, some of these alterations following time courses quite different from the main (HShock) inductions. The heat shock effect is thus much more complicated than previously realized. We purified the HShock:1 protein from heat-shocked human lymphoblastoid cells, and prepared a rabbit antiserum specific for HShock:1 on nitrocellulose two-dimensional gel transfers of total lymphoblastoid cell protein. A survey of mouse tissues shows high concentrations of an HShock:1-like protein in the testis, and human testes also appears to contain substantial (though lower) concentrations. These results are consistent with the hypothesis (derived from the tissue-culture studies) that the heat shock effect is a general response to the need for increased protein catabolism within the cell. Increased concentrations of HShock:1 are also observed in preparations of blood leukocytes collected from patients after surgery, indicating that some types of physiological trauma may induce the heat shock proteins in man. Using the antiHShock:1 antibody in an immunoassay, it will be possible to systematically examine HShock:1 concentrations in plasma and leukocytes, thereby opening up the possibility of a clinical test based for the first time upon an inducible aspect of cellular gene expression.