bluuebunny/crossref_metadata_2025_split huggingface dataset:
Theophylline, dyphylline, caffeine, acetaminophen, salicylate, acetylsalicylate, procainamide, and N-acetylprocainamide determined in serum with a single liquid-chromatographic assay.
Authors: Ou C N , Frawley V L 
Published: January 2020

Abstract
We describe a single set of liquid-chromatographic conditions for assay of theophylline, dyphylline, caffeine, acetaminophen, salicylate, acetylsalicylate, procainamide, and N-acetylprocainamide in serum. The chromatographic system includes a Waters Associates mu-Bondapak C18 column and acetonitrile in 0.1 mol/L potassium phosphate buffer, pH 4.0 (9.75/90.25 by vol), as the mobile phase. Only 50 microL of serum is required, and drug concentrations as low as 0.5 mg/L can be detected. Absolute and relative analytical recoveries range from 95 to 101%. Day-to-day variation of the method is less than 6% for each drug. Linearity extends to 1 g/L for all drugs. Recycling of the mobile phase under pressure eliminates the need to prepare and de-gas solvents. The use of the single stationary and mobile phase provides a practical and economical approach to routine and urgent therapeutic drug monitoring.
Ascorbic acid in lymphocytes: cell preparation and liquid-chromatographic assay.
Authors: Lee W , Hamernyik P , Hutchinson M , Raisys V A , Labbé R F 
Published: January 2020

Abstract
Measurements of ascorbic acid concentration in leukocytes by "high-performance" liquid chromatography (HPLC) provides better nutritional assessment, leading to better management, particularly of presymptomatic and critically ill patients. This procedure includes a simple, reproducible cell-separation technique that requires no more than 2 mL of whole blood. Cell populations are separable with greater than 95% purity and greater than 99% viability. Ascorbic acid is assayed by HPLC. The vitamin can be reproducibly quantified in concentrations as low as 0.1 microgram/mL of cell extract. The chromatographic procedure is very rapid, analysis being completed within 15 min after specimen preparation. The assay is suitable also for urine and protein-free filtrates of plasma and of other biological materials. Reference intervals for plasma, mononuclear leukocytes, and polymorphonuclear leukocytes were established. A preliminary clinical evaluation revealed that hospital patients were at a greater risk of ascorbic acid deficiency than expected.
Mechanism of action of human pancreatic and salivary alpha-amylase on alpha-4-nitrophenyl maltoheptaoside substrate.
Authors: Hägele E O , Schaich E , Rauscher E , Lehmann P , Bürk H , Wahlefeld A W 
Published: January 2020

Abstract
We evaluated the enzymic mechanism by which alpha-4-nitrophenyl maltoheptaoside serves as a substrate for serum amylase (EC 3.2.1.1). Because polymeric substrates possess many potential sites of cleavage, the expression of enzymic activity as the number of micromoles of substrate transformed under defined conditions by an enzyme must be changed to "one microequivalent of group transformed." Therefore, we measured the activity of the isoenzymes of alpha-amylase with regard to suitable oligosaccharide substrates, which allowed us to express the catalytic activity in IUB units (U). By "high-performance" liquid chromatography we investigated the mechanism of human pancreatic and salivary alpha-amylase action, both alone and in combination with alpha-glucosidase (EC 3.2.1.20). On the basis of these results, we can describe exactly the entire reaction sequence and determine the stoichiometric coefficient of 4-nitrophenol within 0.02 mol/L (SD) produced under the assay conditions.
Specific spectrophotometry of ascorbic acid in serum or plasma by use of ascorbate oxidase.
Authors: Liu T Z , Chin N , Kiser M D , Bigler W N 
Published: January 2020

Abstract
We describe a specific enzymatic spectrophotometric method for ascorbic acid in serum or plasma. Samples are analyzed indirectly by measuring the absorbance at 593 nm of a reaction product, a complex of ferrous ion and 2,4,6-tris(2-pyridyl)-s-triazine (Fe2+-TPTZ). This product is formed by reduction of the corresponding ferric ion complex (Fe3+-TPTZ), which is nonspecifically reduced by various biological reducing agents under acidic conditions. Ascorbic acid is specifically quantified by pretreating one of a pair of replicate samples with ascorbate oxidase (EC 1.10.3.3), to oxidize the ascorbic acid, then reacting both samples with Fe3+-TPTZ and measuring the difference between the absorbances at 593 nm of the treated and untreated samples. This difference is linearly related to ascorbic acid concentrations from 10 to 100 mg/L. Ten repeat determinations of a serum pool with added ascorbic acid yielded a CV of 2.8% and a mean of 47.2 mg/L. The correlation (r) between the proposed method and the dinitrophenylhydrazine method was 0.93 for 32 samples analyzed by both methods. The present method is specific for ascorbic acid and requires no deproteinization.
Multivariate delta check method for detecting specimen mix-up.
Authors: Iizuka Y , Kume H , Kitamura M 
Published: January 2020

Abstract
Among laboratory mistakes, "specimen mix-up" is the most frequent and the most serious. According to the Clinical Chemistry Laboratory Error Report of Toranomon Hospital, specimen mix-up was often detected when there were many large discrepancies between the results of a test and the results of a previous test. We present here a checking method to detect specimen mix-up. The method, which we call the "multivariate delta check" method, is an extension of the "delta check" method first presented by Nosanchuk and Gottmann (Am. J. Clin. Pathol. 62:707, 1974). Clinical evaluation has demonstrated the effectiveness of the method.
Evaluation of some critical factors affecting determination of aluminum in blood, plasma, or serum by electrothermal atomic absorption spectroscopy.
Authors: Frech W , Cedergren A , Cederberg C , Vessman J 
Published: January 2020

Abstract
A digestion procedure involving nitric acid is described for determination of aluminum in blood, serum, and plasma by graphite-furnace atomic absorption spectroscopy. Contamination was not a severe problem if all operations were performed in a dust-free atmosphere. Conditions for such determination of aluminum in blood were optimum when the L'vov platform technique was used and hydrogen added to the inner gas flow of the furnace. We discuss the importance of adequate correction for nonspecific absorbance when this technique is used close to the detection limit. The blank value for the overall procedure was 1.0 (SD 0.59) micrograms/L (n = 22). We applied the method to frozen whole blood, plasma, and serum samples. For whole-blood samples from 11 different healthy subjects the mean value was as low as 1.6 (SD 1.29) micrograms of AI per liter (n = 22).
The biological role of enzyme attachment and immobilization.
Authors: Werner M , Garrett C , Chiu A , Klempner L 
Published: January 2020

Abstract
The state of enzymes in the living cell is considered: it is not clear whether some, if any, enzymes are naturally present in the "soluble" state. The evidence for enzyme binding to cellular constituents, and its effects on function and properties of enzyme and isoenzymes, is reviewed.
Enzyme immunoassay of thyroxin-binding globulin.
Authors: Miyai K , Ito M , Hata N 
Published: January 2020

Abstract
We describe a new double-antibody enzyme radioimmunoassay for thyroxin-binding globulin (TBG) in serum. A TBG-beta-D-galactosidase complex was prepared with m-maleimidobenzoyl N-hydroxysuccinimide ester. The mean analytical recovery of TBG added to serum was 99%, sample volume and TBG value were linearly related, and values for TBG determined by this method and those determined by radioimmunoassay correlated well (r = 0.98). Coefficients of variation averaged 7.6% within assay, 6.6% between assay. The measurable range of TBG in the serum was 3.3 to 52 mg/L, but higher TBG concentrations could be measured by diluting the test serum with TBG-free serum. Mean (and SD) serum TBG concentrations as determined by this method were as follows: for 20 normal subjects, 21.2 (3.7) mg/L; for 10 pregnant women, 50.1 (9.5 mg/L; and for 10 patients with TBG deficiency, not detectable.
Systematic error between erythrocyte protoporphyrin in proficiency test samples and patients' samples as measured with two hematofluorometers.
Authors: Balamut R , Doran D , Giridhar G , Mitchell D , Soule S 
Published: January 2020

Abstract
Hematofluorometers manufactured by two different companies (Aviv Biomedical and Environmental Science Associates) performed satisfactorily for protoporphyrin determinations with proficiency test samples but showed about a 30% low bias with actual clinical blood specimens.
Creatine kinase and creatine kinase B-subunit activity in serum in cases of suspected myocardial infarction.
Authors: Gerhardt W , Waldenström J , Hörder M , Hofvendahl S , Billström R , Ljungdahl R , Berning H , Bagger P 
Published: January 2020

Abstract
We evaluated a diagnostic strategy by studying 481 patients suspected of having had an acute myocardial infarction; the prevalence of infarction by independent criteria was 0.43. This strategy is based on the sequential application of: (a) clinical criteria; (b) total creatine kinase determinations in two serum samples drawn within 10 to 20 h of the onset of acute symptoms; and (c) creatine kinase B-subunit (S-CK B) determinations after immunoinhibition with antibodies to creatine kinase M-subunit in the reaction medium in all samples found to have increased total creatine kinase activity. Discrimination limits of 150 U/L total creatine kinase for women and 200 U/L for men gave a diagnostic sensitivity of 0.99. Activities less than these limits in samples identified 68% of the 274 non-infarct cases (posterior probability of a negative result of 0.99) within 20 h. Subsequent determination of S-CK B in 292 patients who were positive by the discrimination limits for total creatine kinase verified myocardial infarction in 99% of 207 cases for which S-CK B exceeded the discrimination limit of 12 U/L. The strategy excluded 98% of all non-infarct cases at a posterior probability of 0.99.
On individual reference intervals based on a longitudinal study of plasma proteins and lipids in healthy subjects, and their possible clinical application.
Authors: Raun N E , Møller B B , Back U , Gad I 
Published: January 2020

Abstract
In a longitudinal study, we determined interindividual and intra-individual variation in 20 plasma proteins and lipids and in other blood constituents by analysis of variance. Blood from 20 healthy subjects was sampled monthly for six months, a rigorous blood-sampling technique being applied. The mean proportion of interindividual variation differed for each blood constituent, ranging from 22 to 91% of the total variation. The possible clinical application of individual reference intervals of this homeostatic model was demonstrated by the fact that they were exceeded in individual cases of upper respiratory tract infection. Concordance between individual reference intervals in healthy controls and in patients--as exemplified in two chronic diseases, multiple sclerosis and chronic inactive pyelonephritis--suggests that the use of individual intervals in (chronic) disease is valid, even when derived from healthy persons. Additionally, sex- and age-related differences were significant for some constituents.
Radioimmunoassay for hepatitis B core antigen.
Authors: Sagnelli E , Pereira C , Triolo G , Vernace S , Paronetto F 
Published: January 2020

Abstract
Serum hepatitis B core antigen (HBcAg) is an important marker of hepatitis B virus replication. We describe an easy, sensitive radioimmunoassay for determination of HBcAg in detergent-treated serum pellets containing Dane particles. Components of a commercial kits for anti-core determination are used, and HBcAG is measured by competitive inhibition of binding of 125I-labeled antibodies to HBcAg with HBcAg-coated beads. We assayed of HBcAG in the sera of 49 patients with hepatitis B surface antigen (HBsAg)-positive chronic hepatitis, 50 patients with HBsAg-negative chronic hepatitis, and 30 healthy volunteers. HBcAg was detected in 41% of patients with HBsAg-positive chronic hepatitis but not in patients with HBsAg-negative chronic hepatitis. Hepatitis Be antigen (an antigen closely associated with the core of Dane particles) determined in the same sera by radioimmunoassay, was not detected in 50% of HBcAg-positive sera.
The cerebrospinal fluid immunoglobulin G index as a diagnostic aid in multiple sclerosis: a Bayesian approach.
Authors: Hische E A , van der Helm H J , van Walbeek H K 
Published: January 2020

Abstract
Having determined immunoglobulin G (IgG) and albumin concentrations in 1100 cerebrospinal fluid and serum samples, we calculated the IgG index. Likelihood ratios for multiple sclerosis were calculated by using a training set consisting of 100 patients with definite multiple sclerosis and one consisting of 97 patients suffering from diseases from which multiple sclerosis must be differentiated. Predictive values for multiple sclerosis, given different values for the IgG index, are given in a graphical representation of Bayes' theorem. We conclude that this approach increases the diagnostic usefulness of the IgG index for the diagnosis of multiple sclerosis.
Six methods for urinary protein compared.
Authors: McElderry L A , Tarbit I F , Cassells-Smith A J 
Published: January 2020

Abstract
Six assays for protein in urine were compared for linearity, ease of standardization, precision, comparability of assay values, technical ease of assay, and current cost. The assays investigated were three dye-binding techniques, a recent turbidimetric technique, the trichloroacetic acid--biuret reaction, and a tannic acid protein precipitation reaction with ferric chloride. All assays suffered from standardization problems, although the biuret method showed the best analytical recovery of albumin and gamma-globulin. The tannic acid/ferric chloride method is dependent on sample pH. The turbidimetric assay exhibited the greatest imprecision; i.e., CVs were 19.5% at a protein concentration of 0.13 g/L and 6.0% at a protein concentration of 1.3 g/L. On the basis of all the factors assessed, we conclude that the Pesce/Strande Ponceau-S and the Bio-Rad Coomassie Brilliant Blue dye-binding techniques offer certain advantages over the other assays studied.
Zinc in plasma, neutrophils, lymphocytes, and erythrocytes as determined by flameless atomic absorption spectrophotometry.
Authors: Whitehouse R C , Prasad A S , Rabbani P I , Cossack Z T 
Published: January 2020

Abstract
Zinc is determined in neutrophils and lymphocytes (isolated from whole blood on discontinuous gradients of Ficoll-Hypaque) and in microliter quantities of plasma and erythrocytes by flameless atomic absorption spectrophotometry with greater sensitivity than with conventional flame atomic absorption spectrophotometry. Before analysis, neutrophils and lymphocytes are digested with nitric acid and diluted with de-ionized water. Plasma and erythrocytes required no digestion, only dilution. Overall CVs were 4.0, 3.0, 5.0, and 4.6% for neutrophils, lymphocytes, erythrocytes, and plasma, respectively. Matrix effects were fully compensated for by use of standard solutions that simulated the sample matrix. Results for plasma and erythrocytes agreed with those obtained by the conventional technique.
Liquid-chromatographic determination of zomepirac in serum and plasma.
Authors: Welch C L , Annesley T M , Luthra H S , Moyer T P 
Published: January 2020

Abstract
We describe a determination of zomepirac concentration in plasma and serum by reversed-phase "high-performance" liquid chromatography. The assay requires 1.0 mL of sample and involves diethyl ether extraction of zomepirac from an acidified sample, followed by concentration and injection into a liquid chromatograph. The column effluent is monitored at 330 nm. Retention times of zomepirac and the internal standard (tolmetin) are 3.8 and 2.7 min, respectively. The lower limit of detection for zomepirac in serum or plasma is 0.05 mg/L. Within-day precision (CV) of analysis in plasma or serum with zomepirac added (0.1-10.0 mg/L) ranged from 1.4 to 6.7%; between-day CV varied from 1.4 to 7.5%. Analytical recovery of zomepirac (1.0 mg/L) from serum and plasma was 77.6 (SD 3.5)% and 80.4 (SD 5.2)%, respectively. Numerous commonly coadministered drugs did not interfere. The elimination half-life of the drug was 1.8 h, and the peak plasma concentration ranged from 1.1 to 2.4 mg/L. Peak and trough concentrations measured throughout five days of therapy imply no accumulation.
Radioimmunoassay for somatomedin C: comparison with radioreceptor assay in patients with growth-hormone disorders, hypothyroidism, and renal failure.
Authors: Baxter R C , Brown A S , Turtle J R 
Published: January 2020

Abstract
We raised an antiserum (Tr4) in rabbits against a basic somatomedin C-like peptide preparation. Using high-immunoreactivity somatomedin C tracer, we compared the performance of radioimmunoassays in which we used the Tr4 antiserum and a well-characterized somatomedin C antiserum distributed by the National Pituitary Agency (NPA) with that of the human placental-membrane somatomedin radioreceptor assay (RRA). In their cross reactivity toward various somatomedin-like and unrelated peptides, the two radioimmunoassay methods were almost identical, although NPA antiserum, with about fourfold higher titer than Tr4 antiserum, showed a slightly greater sensitivity for most peptides tested. Radioimmunoassay of acid-ethanol-extracted plasma samples from normal persons and acromegalic, hypopituitary, hypothyroid, and renal-failure patients revealed no analytical differences between the antisera (for 122 samples, r = 0.979 between methods). Somatomedin values for acromegalic and hypopituitary samples showed no overlap with normals. Values for hypothyroid and pre-dialysis renal-failure samples were significantly lower than normal. By comparison, the RRA showed greater cross reactivity toward some somatomedin-like peptides and gave significantly lower values than radioimmunoassay for acromegalic and hypothyroid plasma extracts, and significantly higher value for hypopituitary and renal-failure samples. We conclude that the radioimmunoassay methods clearly are of greater diagnostic value than RRA for clinical somatomedin measurement.
Uric acid determinations: reversed-phase liquid chromatography with ultraviolet detection compared with kinetic and equilibrium adaptations of the uricase method.
Authors: Ingebretsen O C , Borgen J , Farstad M 
Published: January 2020

Abstract
A reversed-phase liquid-chromatographic procedure is presented for quantitation or uric acid in human serum, with absorbance measured at 292 nm. The mobile phase was sodium acetate (35 mmol/L, pH 5.0)/acetonitrile (9/1 by vol). Complete precipitation of serum proteins was obtained by mixing serum (50-500 microL) with an equal volume of acetonitrile, and the precipitate was removed by centrifugation. Aliquots (20 microL) of the supernate were injected directly into the liquid chromatograph, which was adjusted so that the absorbance reading of the uric acid peak was as high as possible. Routinely, a full-scale deflection of 1.28 absorbance units was used. The within-run precision (CV) was 0.6% for a serum uric acid concentration of 227 mumol/L and day-to-day precision over a 15-day period was 0.8% for uric acid of 345 mumol/L. No interferences from related compounds were observed. We compared results by this method with those by kinetic (aca, Du Pont) and equilibrium adaptations (Ames kit; Nyco-test, Nyegaard; and Monotest, Boehringer Mannheim) of uricase methods. The method we report is simple, and can be used in a fully automatic liquid-chromatographic system.
Nephelometric measurement of ceruloplasmin with a centrifugal analyzer.
Authors: Pesce M A , Bodourian S H 
Published: January 2020

Abstract
We describe a rapid nephelometric assay for measurement of ceruloplasmin in serum with the Multistat centrifugal analyzer. In establishing the optimum conditions, the concentration of polyethylene glycol was critical. With a 30 g/L solution of polyethylene glycol, the calibrators and samples react at the same rate, while with a 60/L solution the calibrators react faster than the samples. The reaction rate was not affected by temperatures of 30 or 37 degrees C or pHs between 6.0 and 8.4. There was no interference from bilirubin at a concentration of 180 mg/L, hemoglobin at a concentration of 5000 mg/L, or lipemic serum. The standard curve extends from 50 to 1300 mg/L. Analytical recovery of ceruloplasmin added to four serum specimens averaged 97%. The within-run precision (n = 17) gave CVs of 5.4, 6.1, and 4.0% for samples containing ceruloplasmin at concentrations of 240, 360, and 650 mg/L. Ceruloplasmin concentrations measured by our procedure were compared with those obtained by nephelometric, radial immunodiffusion, and enzymic procedures; the correlation coefficients were 0.93, 0.88, and 0.86.
High-density lipoprotein cholesterol and phospholipids, and apoprotein A in serum of patients with liver disease.
Authors: Rubiés-Prat J , Masdeu S , Nubiola A R , Chacón P , Holguera C , Masana L 
Published: January 2020

Abstract
Concentrations of apoprotein A in whole serum, and cholesterol and phospholipids concentrations in the high-density lipoprotein fraction of serum were measured after the precipitation of low-density and very-low-density lipoproteins with sodium phosphotungstate-Mg2+ in 23 patients with liver cirrhosis, 19 patients with extrahepatic biliary obstruction, and 20 healthy control subjects. Patients with cirrhosis and cholestasis showed approximately one-half as much cholesterol and apoprotein A in the nonprecipitable high-density lipoprotein fraction as normal subjects did. High-density lipoprotein phospholipids concentrations in those patients were normal or slightly increased, however, which is about double what one would expect from the apoprotein A and cholesterol content.
Three radioligands compared for determining cytoplasmic estrogen-receptor content of human breast carcinomas.
Authors: Pieslor P C , Gibson R E , Eckelman W C , Oates K K , Cook B , Reba R C 
Published: January 2020

Abstract
We compared three radioligands for use in a cytoplasmic estrogen-receptor assay, using pooled cytosol from human breast adenocarcinomas. The estrogen receptor content was determined in vitro by a dextran-coated charcoal method involving a 4-h incubation with and without diethylstilbestrol. Tritiated moxestrol failed to come to equilibrium in 4 h, thereby preventing the use of conventional one-component Scatchard analysis. The use of 125I-labeled estradiol resulted in a higher estimate of estrogen-receptor concentration than that obtained with use of tritiated estradiol. This overestimation was not corrected by Scatchard, double-reciprocal, or Woolf plots, or by two different methods of data analysis: least squared and "robust." An underestimation of the specific activity of iodoestradiol with respect to that of tritiated estradiol and an unrecognized second component of nonreceptor binding could explain this disparity.