bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluation of the Corning 940 Calcium Titrator for Use with Serum and Urine
Authors: Weissman Earl B , Pragay Desider A , Bishop Charles
Published: January 2020

The Corning 940 Titrator, which measures total calcium concentration by titration with [ethylenebis(oxyethylenenitrilo)]tetraacetic acid, was evaluated for use in a hospital laboratory. Calcium values for patients' sera were about 0.3 mg/dl lower as measured with the Titrator than with the Technicon SMA 12/60 continuous-flow analyzer. A similar bias was evident when the results with the Titrator were compared with those from atomic absorption spectrophotometry. Agreement was better in the low range and worse in the high range. Within-day and between-day coefficients of variation on the Titrator were about 1.5% and 2.5%, respectively. We saw no interference from magnesium, phosphorus, bilirubin, or in the presence of lipemia. At extremely increased hemoglobin concentrations (500 mg/dl), there is a 5% inhibition. Titrator results for patients' urine samples correlated closely (n = 0.999) with those obtained with the SMA 12/60.
The Potential of Phosphorescence Spectrometry in Clinical Chemistry—The New Generation of Instrumentation and Methodology
Authors: O'Donnell C M , Winefordner J D
Published: January 2020

We review recent advances in instrumentation and methodology in phosphorimetry that should facilitate the use of phosphorimetry for clinical analyses and recent phosphorescence studies of interest to the clinical chemist. We indicate recent advances, particularly improvements in instrumentation, novel methodologies, and new chemical processes that result in either an increase in sensitivity or selectivity (or both) of measurement of compounds of clinical importance. The greatest use of phosphorimetry in the clinical laboratory will not be for the analysis of very large numbers of samples for one species via automatic instrumentation, but rather will be for the analysis of those molecular species difficult or impossible to measure by conventional methods (colorimetry, fluorometry, etc.). Although various instrumental and methodological advances are discussed separately here, the most important use of these advances in clinical chemistry will undoubtedly be when two or more of them are combined, for example, in the use of time- or frequency-resolved phosphorimetry for the selective measurement of the phosphorescence resulting with inorganic probes and the appropriate choice of solvent and pH (of course, the instrument could contain an image vidicon detector for rapid determination of the spectrum, the decay curve, or both).
The Impact of Laboratory Error on the Normal Range: A Bayesian Model
Authors: Krause R D , Anand V D , Gruemer H D , Willke T A
Published: January 2020

Interpretation of clinical laboratory results, aside from clinical considerations, is based on the probability of the result being within a given normal range. This probability is influenced by the degree of error inherent in the analytical method. It would be advantageous to assign a more definite probability to the result of the measurement by combining the error distribution of the result around the true value and the distribution of the healthy population that serves as a reference. Bayesian statistics permits the revision of this prior information into a single probability.
Assay of L-Tyrosine in Serum by Amperometric Measurement of Tyrosinase-catalyzed Oxygen Consumption
Authors: Kumar Anand , Christian Gary D
Published: January 2020

A new enzymatic method for rapid direct measurement of serum tyrosine is described, based on the amperometric measurement of the rate of oxygen consumption when tyrosine is oxidized in the presence of the enzyme tyrosinase in a phosphate buffer (0.1 mol/liter, pH 7.4). A Beckman Glucose Analyzer with a Clark electrode is used for the measurement. The procedure does not require removal of serum protein, incubation nor extraction, and results are obtained in less than 1 mm. Results agree closely with those obtained by a fluorometric procedure and with an amino acid analyzer.
Comparison of Results for Morphine Urinalyses by Radioimmunoassay and Thin-Layer Chromatography in a Narcotic Clinic Setting
Authors: Kokoski Robert J , Jain Mishrilal
Published: January 2020

Radioimmunoassay (RIA) and thin-layer chromatography (TLC) were compared for morphine detection in an actual narcotic clinic setting. A choice of urines from all those screened by TLC allowed a critical comparison as to actual use or non-use of narcotic drugs, rather than a sampling at random in which the question of possible false positives or negatives cannot be conclusively answered. Although RIA is more sensitive than TLC, its advantage is apparent only in those cases where urine specimens are difficult to obtain frequently regularly or where the use of morphine is suspected by the positive identification of quinine in urine that was morphine-negative by TLC. In a selected group of negative and positive specimens chosen without conscious bias, the two methods gave consistently similar results, indicating that the modified TLC method provided few or no false positives or negatives if the negatives were from those cases that were not positive anytime up to 3-4 days before urine collection. We conclude that RIA can be of significant value as a supplement to a TLC screening program, without sacrificing the many advantages that TLC has to offer.
Newer Aspects of the Roles of Zinc, Manganese, and Copper in Human Nutrition
Authors: Burch Robert E , Hahn Henry K J , Sullivan James F
Published: January 2020

Advances in knowledge of the trace elements zinc, manganese, and copper are reviewed (151 references), particularly as related to human metabolism and disorders. The literature reviewed, with few exceptions, is that published by December 1973.
Serum Zinc, Iron, and Copper Concentrations during Typhoid Fever in Man: Effect of Chloramphenicol Therapy
Authors: Pekarek Robert S , Kluge R M , DuPont H L , Wannemacher R W , Hornick R B , Bostian K A , Beisel W R
Published: January 2020

In volunteers experimentally infected with Salmonella typhi, serum iron and zinc concentrations became significantly depressed and there was a concomitant rise in serum copper before the onset of overt clinical illness. However, after several days of fever and the initiation of chloramphenicol therapy, serum iron and zinc concentrations significantly increased. Additional studies—in volunteers with typhoid fever treated with chloramphenicol, in a volunteer with typhoid fever receiving cefazolin and gentamicin, and in untreated rhesus monkeys infected with Salmonella typhimurium—provided evidence that the increase in serum iron concentration during the febrile phase was the result of chloramphenicol therapy, whereas the increase in serum zinc concentrations was a disease-related phenomenon. The importance of trace-metal monitoring during infectious disease and chemotherapy is discussed
Retention of Fluoride with Time in Man
Authors: Spencer Herta , Osis Dace , Wiatrowski Emilie
Published: January 2020

Fluoride retention is high during fluoride supplementation and increases with increasing fluoride intake. When large amounts of fluoride were given for several months the retention of fluoride was about the same as in the initial phase of fluoride supplementation, whether the supplemental dose of fluoride was 10, 20, or 45 mg per day. The rapid return of the fluoride balance to control values after the high fluoride intake was discontinued indicates that there is not only a tendency for continued retention of fluoride during the high fluoride intake but also after large amounts of fluoride have already been retained.
Determination of Serum Copper by Atomic Absorption, with Use of the Graphite Cuvette
Authors: Evenson Merle A , Warren Brenda L
Published: January 2020

We have established and evaluated a flameless graphite cuvette method for copper in serum. This atomic absorption method provides substantial improvement in sensitivity, adequate accuracy, and acceptable precision, and little sample preparation is required before the analysis. Standard addition studies and measurements of National Bureau of Standards materials indicated that the proposed method is accurate, but that sample pH must be kept between 2 and 3 for high accuracy. Cations and anions that frequently are present in proteincontaining samples do not interfere significantly. Sample cross contamination in the syringe must be carefully avoided. Finally, when results for more than 100 patients' sera by this method were compared to those obtained by flame atomic absorption for the same samples, no substantial bias or inaccuracies could be attributed to this new micro-scale method for serum copper. Hence, this method is ideally suited for use on pediatric patients.
Linear Working Graphs in Blood Lead Determinations with the Beckman Flameless Atomic Absorption Cuvet
Authors: Kilroe-Smith T A
Published: January 2020

Working graphs are generally nonlinear when the longitudinal flameless atomic absorption cuvet is used. Such nonlinear curves make it difficult to determine the amount of lead in blood by the method of additions, because of inaccuracies in extrapolating the graph to zero absorbance. This paper describes a method for obtaining linear graphs by making use of opacity (the reciprocal of transmittance, or antilog of the absorbance) instead of absorbance. Because no deuterium arc background corrector is available for the Beckman Model 444, background was corrected by reading the opacity at a nonabsorbing line, 287.3 nm, and subtracting the opacities. A separate reagent-blank correction for lead must also be made.
Comparison of Radioimmunoassay with Thin-Layer Chromatographic and Gas—Liquid Chromatographic Methods of Barbiturate Detection in Human Urine
Authors: Roerig David L , Lewand Donna L , Mueller Marilyn A , Wang Richard I H
Published: January 2020

A radioimmunoassay (I) for barbiturates was compared with thin-layer chromatographic (II) and gas—liquid chromatographic (III) methods for barbiturate detection in human urine. Timed urine samples were obtained from volunteers who had ingested 100 mg of a barbiturate. I detected barbiturate in all urines tested up to 76 h after the dose, and III in all up to 52 h and in 90% up to 76 h. II detected barbiturates in 90% of all urine samples for only 30 h, after which its reliability declined. Glutethimide interfered with radioimmunoassay of barbiturate, producing false positives. I is sensitive, reliable, and fast, and lends itself to screening large numbers of urine samples for barbiturates. For routine urine surveillance, however, we found I to be less useful than II, which is still the method of choice. I has, however, proved to be an excellent method for confirming resuits of II.
Automated Determination of Serum Ceruloplasmin Activity with o-Dianisidine Dihydrochloride as Substrate
Authors: Schosinsky Karl H , Lehmann Peter , Beeler Myrton F
Published: January 2020

An automated method for the enzymatic determination of ceruloplasmin with o-dianisidine dihydrochioride as substrate is described. The method enables the measurement of 30 samples per hour with a coefficient of variation (day-to-day) of 2.8%. Results correlate well (r = 0.99) with those obtained by the corresponding manual method.
The Scope of Mass Spectrometry in Clinical Chemistry
Authors: Lawson Alexander M
Published: January 2020

Several aspects of mass spectrometry and gas chromatography—mass spectrometry are reviewed, including ionization methods, repetitive scanning, selected ion monitoring, and stable isotope measurement. I discuss the application of these and other mass spectrometry methods to the investigation of compound classes relevant to clinical chemistry, to the assessment of inborn errors of metabolism, and to clinical studies. The latter include consideration of volatiles in body fluids, respiration and blood gases, stable-isotope applications, clinical toxicology, and drugs.
Citrate Synthesis by Lymphocytes
Authors: Dixit Padmakar K , Cadwell Ruth
Published: January 2020

The important role of lymphocytes in humoral and cellmediated immunity indicates that they need a readily available intracellular source of energy. Here, we demonstrate that these cells contain enzymes involved in citrate formation. The citrate is oxidized through the tricarboxylic acid cycle to furnish energy. A newly devised, simple radiometric method was used to determine the condensation of labeled acetate or acetyl CoA with oxaloacetate to form citrate. The de novo synthesized citrate was oxidized to pentabromoacetone, and radioactivity of the resulting CO2 was directly related to the amount of citrate synthesized. Both lymphocytes from chronic lymphatic leukemia patients and cultured lymphoblasts possess this active citrate-synthesizing apparatus, although the lymphoblasts appeared to have a considerably higher activity, perhaps because they are larger.
Computer-Controlled Automation of Radioimmunoassay Based on Gel Entrapment of Antibody
Authors: Cottrell David B , Toren E Clifford , Magnuson Judith A , Updike Stuart J
Published: January 2020

We describe a new, broadly applicable approach to radioimmunoassay. Solid-phase binding reagent is prepared by entrapping antibody in polyacrylamide gel. This gel is then fragmented, sieved, and dehydrated in 95% ethanol. Upon evaporation of the ethanol, the dry antibody—gel particles are dispensed into miniature disposable plastic columns. A unidirectional flowing stream configuration is used to construct a standard curve for the polypeptide hormone, angiotensin I, used here to exemplify the technique. Good reproducibility of this standard curve is demonstrated. The analytical system includes a computer-controlled sample turntable, digital pipet, and liquid-switching assembly.
Comparison of Five Radioimmunoassays and Enzyme Bioassay for Measurement of Digoxin in Blood
Authors: MacKinney Archie A , Burnett George H , Conklin Robert L , Wasson Gertrude W
Published: January 2020

Digoxin-containing sera from 86 patients were analyzed for this drug by bioassay and radioimmunoassay. Each serum was analyzed in duplicate by six procedures: inhibition of Na+-K+-dependent ATPase and five "kit" radioimmunoassays from four different commercial sources. Mean values for two of the radioimmunoassays differed significantly from those for the bioassay. One radioimmunoassay mean value was significantly different from the other five mean values. We conclude that normal values for digoxin radioimmunoassay should be determined for each kit, and should not be adopted from published data.
Enzyme Activities of NADPH-Forming Metabolic Pathways in Normal and Leukemic Leukocytes
Authors: Belfiore Francesco , Borzi Vito , Lo Vecchio Luigi , Napoli Elena , Rabuazzo Agata M
Published: January 2020

With respect to the enzymes of NADPH-forming metabolic pathways in human leukocytes: (a) Glucose-6phosphate dehydrogenase and phosphogluconate dehydrogenase (decarboxylating) were less active in leukocytes (mostly myeloblasts) from eight patients with acute myeloblastic leukemia (I) than in leukocytes (mostly granulocytes) from 16 normal subjects (II) or 16 patients with chronic myelocytic leukemia (III). (b) Of the enzymes of the citrate cleavage pathway, ATP citrate lyase and malate dehydrogenase (decarboxylating) (NADP+) were virtually absent in the cells studied. (c) Isocitrate dehydrogenase (NADP+), aspartate aminotransferase, and alanine aminotransferase, which, together with the much more active malate dehydrogenase, constitute a newly proposed NADPH-forming metabolic cycle, showed a higher activity in I than in II or III, and therefore could compensate, as concerns NADPHgeneration, for the low activity of pentose cycle dehydrogenases. We are not sure whether the enzymatic characteristic of I cells is attributable to their immaturity or to their leukemic nature.
Use of High-Resolution Open Tubular Glass Capillary Columns to Separate Acidic Metabolites in Urine
Authors: Knights Brian A , Legendre Mary , Laseter John L , Storer James S
Published: January 2020

We used high-resolution glass capillary columns to study the trimethylsilyl derivatives of some acidic metabolites found in pooled urine specimens from control and postpartum subjects. About 30 compounds were identified by gas chromatography—mass spectrometry—computer techniques. In general, open tubular capillary columns effect better resolution of trimethylsilyl derivatives of organic acids than do conventional packed columns. GE SE-30 proved to be a good general-purpose stationary phase, whereas OV-17 offered certain advantages in resolving aromatic acid components.
Correction for Spectral Interference with Determination of Lead in Blood by Non-Flame Atomic Absorption Spectrometry
Authors: Garnys V P , Matoušek Jaroslav P
Published: January 2020

A non-flame atomizer incorporating a graphite tube and cup is used to determine lead in whole blood and packed erythrocytes. In a direct method, a 2-µl sample is treated in situ in the cup with 1 µl of concentrated nitric acid. The oxidized sample can then be dried, ashed, and atomized without leaving a residue. The nitric acid treatment obviates correction for nonselective absorption, something previously necessary in the determination of lead in blood by non-flame techniques. The resulting chemical conversion of the matrix compounds frees the lead atomic absorption peak from the spectral interference. Alternatively, a 50-µl sample of blood or erythrocytes is treated with 50 µl of concentrated nitric acid and a 1.5-µl aliquot is analyzed with use of the graphite tube.
Inhibitory Effect of Fluoride on Glucose Tests with Glucose Oxidase Strips
Authors: Onstad John , Hancock Daniel , Wolf Paul L
Published: January 2020

Sodium fluoride was inadvertently added as a preservative to the urine of an eight-year-old boy with diabetes mellitus before urinary glucose was measured. On preliminary screening of the urine, the test by glucose oxidase paper reagent strip gave a negative reading for glucose, whereas quantitative urinary glucose assay by the coupled enzyme reaction (hexokinase—glucose 6-phosphate dehydrogenase) gave a glucose concentration of 81.5 g/liter. Inadvertent use of sodium fluoride as a urine preservative may cause a falsely negative result with the glucose tests involving oxidase.
Immunological Measurement of Transferrin Compared with Chemical Measurement of Total Iron-Binding Capacity
Authors: Tsung Swei H , Rosenthal Waldemar A , Milewski Karen A
Published: January 2020

Because of uncertainty as to the molecular weight of transferrin, a previous comparison [Von der Heul et al., Clin. Chim. Acta 38, 347 (1972)] between transferrin content of serum and total iron-binding capacity cannot be definitive. We found a conversion factor for expressing transferrin as iron-binding capacity by measuring the maximum amount of iron bound by 1 mg of transferrin. We compared the resulting calculated value with values obtained by three other methods for measuring total iron-binding capacity. We agree with the previous observation that the latter, as measured radioisotopically, give higher results than would be judged from the transferrin content but the same as those for two chemical methods. The diffusion rate of transferrin in agar was the same irrespective of the degree of iron saturation. Serum transferrin concentrations were low in patients with anemia resulting from malignancy, chronic disorders, and cirrhosis of the liver, and high or normal in patients with iron deficiency anemia and in pregnant women or women who were taking birth-control pills. Measurement of transferrin concentration can be used to distinguish iron deficiency anemia from anemia resulting from chronic disorders, but offers no advantages over existing methods for estimating total ironbinding capacity.
Aspartate Aminotransferase and Alanine Aminotransferase Activities in Plasma: Statistical Distributions, Individual Variations, and Reference Values
Authors: Siest Gérard , Schiele Françoise , Galteau Marie-Madeleine , Panek Edwige , Steinmetz Josiane , Fagnani Francis , Gueguen René
Published: January 2020

The determination of frequency value (percentile limits) and the classification of the different variation factors allow us to define more and more homogeneous subpopulations as we use these factors for sorting. Using as our study population those persons coming to the Centre for Preventive Medicine, we were able to: (a) Describe and measure the significance and importance of physiological variations or of variations attributed to age—the latter largely related only to excessive weight, which it seems to us is often the case. (b) Establish a classification for variation factors; the recapitulatory table should be useful to clinical chemists in helping physicians interpret a laboratory test result that falls within the zone of incertitude. (c) Suggest a preliminary group of reference values for healthy subjects, to be used in interpreting a laboratory test in this way.
Standards for Total Serum Protein Assays— A Collaborative Study
Authors: Doumas Basil T
Published: January 2020

We have studied the standardization of total serum protein assay with the biuret reaction. Standard solutions were prepared from lyophilized preparations of human serum albumin and bovine serum albumin, with corrections made for volatile material and ash contents. These solutions and a solution of crystalline albumin standard were analyzed with a new stable biuret reagent, to establish absorptivity values (values for the absorbance of a 1 g/liter final reaction mixture). The mean values obtained were 0.302, 0.292, and 0.290 for human serum albumin, bovine serum albumin, and the crystalline albumin, respectively. We believe that the established absorptivity value will improve the accuracy of serum protein determinations. We studied the linearity of the relation between color produced and protein concentration, with use of the solutions described above and a serum pool. The color adheres to Beer's law up to the highest concentration tested: 3 g/liter for HSA and BSA, and 2.8 g/liter for serum in the final reaction mixture. The new biuret reagent has been stable for one year at room temperature. We recommend the use of bovine serum albumin as a primary standard for serum protein assays. It is inexpensive, easily available, and exhibits the best linearity in the biuret reaction.
Standardization of Incubation Time and Temperature for Eight Radioimmunoassays
Authors: Lenz Paul H , Wien George H , Toth Janice M
Published: January 2020

We wanted to know if incubation time and temperature for many radioimmunoassay methods could be standardized, to decrease assay time and so improve efficiency. Percentage binding was determined for triiodothyronine, thyroxine, digoxin, digitoxin, testosterone, aldosterone, estradiol, and diphenylhydantoin when the reaction mixtures were incubated at 6-8, 22, or 37 °C for various periods of time. In all methods tested, binding of antigen to antibody was greatest when the reaction mixtures were incubated at 6-8 °C, less at 22 °C, and least at 37 °C. Maximum binding occurred within 30-60 min at each temperature for all methods tested. Hence, it is possible to standardize the incubation time and temperature for these eight radioimmunoassay methods to 60 min at 6-8 °C.
Continuous Monitoring of Radioactivity of Effluent from a High-Speed Amino Acid Analyzer, with a New System of Sample Segmentation
Authors: Bakay Bohdan
Published: January 2020

Radioactivity in the effluents from high-speed liquid chromatographic analyzers was continuously measured by use of a new sample segmentation system. To achieve highest counting efficiency, the column effluents were mixed with scintillation fluid carrying small segments of semisolid, resilient spacer. After passing through a mixer, the mixture was passed through a hollow-tube flow cell mounted in a liquid scintillation spectrometer. Because the added spacer acts like a continuous series of pistons, it unifies flow rate at center and walls of the conduit and so decreases sample carryover. This system was applied to measurement of radioactivity in the effluent of a high-speed amino acid analyzer, in which some amino acids emerge at 30-s intervals. The resulting profiles were as well resolved as were the ninhydrin-color profiles. Counting efficiencies for tritium and carbon-14 were comparable to those obtained by static counting in vials.
New Instrument for Rapid Determination of Activities of Lactate Dehydrogenase Isoenzymes
Authors: Everse Johannes , Reich Richard M , Kaplan Nathan O , Finn W Donald
Published: January 2020

Lactate dehydrogenase isoenzymes can be distinguished kinetically by the fact that isoenzyme H is strongly inhibited a few seconds after the reaction is started if high concentrations of pyruvate are present, in contrast to the M isoenzyme. A new instrument that exploits this fact can measure both the total activity and the proportion of H isoenzyme in serum or plasma in 8 to 10 s. The instrument consists of a simplified stoppedflow apparatus in which the plasma is assayed for lactate dehydrogenase activity, and an electronic device that measures the rate of the reaction at two pre-set time intervals. The first rate is taken between 0.2 and 0.4 s after the reaction is started, a time at which both isoenzymes are fully active, and at which the rate obtained thus reflects total lactate dehydrogenase activity in the plasma sample. The second rate is measured 4 to 6 s after the start of the reaction, at which time the H isoenzyme has become inhibited and the observed rate compared to the initial rate is therefore proportional to the percentage of H isoenzyme activity in the serum. These two rates are electronically displayed on two three-digit voltmeters, the first display being the total activity, the second a number proportional to the inhibited slope. The percentage of M isoenzyme can then be calculated from the initial and final rate. A total of five to six repeat assays may be done within a minute on 1 ml of plasma or serum. This instrument may be of significant value in following the progress of myocardial infarctions and other diseases.
Clinical Applications of Gas Chromatograph/Mass Spectrometer/Computer Systems
Authors: Horning Marjorie G , Nowlin Jean , Butler Carla M , Lertratanangkoon Khing , Sommer Kathleen , Hill Reba M
Published: January 2020

Gas chromatograph/mass spectrometer/computer systems can be used to quantify a wide variety of compounds of clinical interest. A quadrupole instrument operated in the chemical ionization (Cl) mode was used in these studies. Because of the sensitivity and specificity of selective ion detection, it is possible to make measurements routinely in the nanogram to picogram range, with 0.1-1.0 ml samples of plasma and 1-5 ml samples of urine. Internal standards, preferably stable-isotopelabeled compounds, were added to the biological samples before isolation was begun. We describe clinical applications of these procedures to problems in toxicology, pharmacokinetics, and perinatal pharmacology.
Gas-Chromatographic and Mass-Spectrometric Detection of Low-Molecular-Weight Aliphatic Alcohols in Urine of Normal Individuals and Patients with Diabetes Mellitus
Authors: Liebich Hartmut M , Al-Babbili Ossama , Zlatkis Albert , Kim Kyoung
Published: January 2020

We studied the aliphatic alcohols in 100 urines from 25 patients with diabetes mellitus under treatment with insulin, oral antidiabetic medication, or special diet. The procedure involves adsorption of the low-molecular-weight urinary metabolites on a porous polymer of 2,6-diphenyl-p-phenylene oxide (Tenax GC), gas-chromatographic separation, mass spectrometric identification, and mass fragmentographic representation of the primary alcohols by a computer. The concentrations of ethanol, n-propanol, isobutanol, n-butanol, and isopentanol are increased as compared with urine from normal persons.
Effects of storage in the cold on activity of gamma-glutamyltransferase in serum.
Authors: Rhone D P , White F M
Published: January 2020

Sera from patients with hepatobiliary disorders were selected to represent a wide range of activity of gamma-glutamyltransferase (EC 2.3.2.2). Samples were stored at 4 degrees C and periodically tested for as long as nine weeks, others at -6 degrees C for as long as 40 weeks. The frozen-stored samples were thawed and then frozen again after each testing. The activity of the enzyme was essentially unchanged under both conditions of storage. These results are consistent with comments in the literature on the enzyme's stability.
Recently discovered hypothalamic-pituitary hormones.
Authors: Malarkey W B
Published: January 2020

In recent years a variety of peptide hormones have been isolated from the mammalian hypothalamus and pituitary. Several hypothalamic hormones, including thyroliberin (thyrotropin-releasing factory), luliberin (luteinizing hormone-releasing factor), and somatostatin (somatotropin release-inhibiting factor), have been characterized and synthesized. The subsequent development of radioimmunoassays for these hormones has made possible the study of their physiology. The measurement of prolactin in serum and the release of pituitary hormones after the administration of the hypothalamic hormones has proved to be useful in clinical diagnosis. The use of hypothalamic hormones in treating various clinical disorders and the isolation and characterization of new releasing and inhibiting hormones in the hypothalamus are actively being investigated.
Improved microscale assay for purine phosphoribosyltransferase activities.
Authors: Schmidt R , Forêt M , Reichert U
Published: January 2020

We describe an improved and rapid filter-type assay for purine phosphoribosyltransferase activities. 14C-labeled purine bases are used as substrates, and the equipment includes a sampling manifold and glass-fiber filters coated with polyethyleneimine-cellulose. The method is especially suited for assay of a large number of samples, and may be useful for other enzyme activity measurements.
Evaluation of a reagent-strip method for glucose in whole blood, as compared with a hexokinase method.
Authors: Stewart T C
Published: January 2020

The hexokinase method (I) for glucose in biological fluids, proposed by the FDA as a potential national standard method, is compared with the Eyetone/Dextrostix/Control method (II) for measurement of glucose in whole blood. I used a new, two-step calibration procedure based on a 1.30 g/liter standard for the II system. The correlation coefficient for results by the two methods was 0.99 for 142 assays in duplicate. Recovery values were near 100% (I, range 100.0 to 106.2%; II, range 100.8 to 105.1%), and the coefficients of variation were respectively +/- 4.1% and +/- 4.5%. Considering the close correlation between the two methods, together with the simplicity, speed, and convenience of II, I conclude that it has great clinical utility, particularly in emergency situations. The precision and accuracy of II depends greatly on proper calibration and control procedures and on adequate training of the operator.
Spectrophotometric end-point method for assay of serum cystyl-aminopeptidase in pregnancy.
Authors: Durham B H
Published: January 2020

An optimized end-point method that requires little sophisticated equipment is described for estimating serum cystyl-aminopeptidase during pregnancy. S-Benzyl-L-cysteine-4-nitroanilide is used as the substrate.
Automated method for L-carnitine determination.
Authors: Seccombe D W , Dodek P , Frohlich J , Hahn P , Skala J P , Campbell D J
Published: January 2020

Because of renewed interest in a possible connection between carnitine, lipid disorders, and myopathy, an automated method of analysis is desirable. Deproteinization of serum by use of membrane filter cones and automated assay with a bichromatic analyzer (the ABA-100) substantially increases efficiency without sacrificing the specificity and accuracy of the original manual enzymatic method. The described procedure allows for analysis of 80 speciments a day and is thus suitable for screening of selected populations. Normal values found in blood sera of adults were in the range of 25.0-73.8 mu mol/liter and the method has sufficient sensitivity to accurately measure concentrations as small as 10 mu mol/liter.
Comparison of procedures for extracting free amino acids from polymorphonuclear lekocytes.
Authors: Houpert Y , Tarallo P , Siest G
Published: January 2020

We studies five methods for extracting amino acids from human polymorphonuclear leukocytes. Both the use of cell lysis and of a deproteinizing agent interfere with quantitative determination of the amino acids, basic amino acids being the most sensitive to the extraction procedure. Among the methods used, disruption of the cells by freezing-thawing is the best method for extracting all the amino acids. Taurine is the only amino acid extracted in the same amount by all the methods studied, and it represents half of the intracellular pool.
Serum alkaline phosphatase measured by using thymol blue monophosphate and a bichromatic analyzer.
Authors: Elser R C
Published: January 2020

Thymol blue monophosphate is evaluated as a substrate for use in kinetic bichromatic analysis of serum alkaline phosphatase activity. The effect of abnormally high concentrations of hemoglobin, bilirubin, or chylomicrons is negligible. The expected range for ambulatory adults established by assaying sera from 206 blood donors, was 12-44 U/lliter at 37 degrees C. Comparison of the method with a commonly used p-nitrophenyl phosphate method yielded a correlation coefficient, r, of 0.9949. Advantages of the method are the reduced cost per test and the exceptionally stable substrate.
Toward absolute methods in clinical chemistry: application of mass fragmentography to high-accuracy analyses.
Authors: Björkhem I , Blomstrand R , Lantto O , Svensson L , Ohman G
Published: January 2020

We review recently developed reference methods based on mass fragmentography (specific ion monitoring) with use of isotope-labeled internal standard, for determination of cholesterol, triglycerides, urea, glucose, cortisol, progesterone, and testosterone. With an optimal ratio between standard and material to be determined, the relative standard deviation of these methods, based on duplicate determinations, is between 1.3 and 2.7%. The very high specificity of the methods, in combination with the fact that the ratio between labeled and unlabeled molecules is determined with a high degree of accuracy, makes it likely that the most significant errors in the methods are related to errors in pipetting. The possibility is discussed that these methods might be developed into "absolute" or "definitive" methods by subjecting each individual step in the determination to a detailed analysis with respect to possible error. We also discuss some of the consequences of the different reference methods on the choice of routine methods.
Metabolic response of humans to ingestion of nicotinic acid and nicotinamide.
Authors: Mrochek J E , Jolley R L , Young D S , Turner W J
Published: January 2020

The identification of nicotinamide-N1-oxide as a metabolite in the urine of a schizophrenic patient prompted a study of the relative metabolism of nicotinic acid and nicotinamide in mental patients and healthy volunteers. Metabolites quantified included N1-methyl-2-pyridone-5-carboxamide, N1-methyl-4-pyridone-3-carboxamide, N1-methylnicotinamide, nicotinuric acid, and nicotinamide-N1-oxide. More of most of these metabolites evidently was excreted after nicotinamide ingestion than after nicotinic acid. At the highest doses (3000 mg/day), the relative proportions of these metabolites in the urine were changed. There were only slight difference between healthy individuals and mental patients in the quantities of metabolites excreted, and no statistically significant trends were noted.
Evaluation of three commercially available menual "kit" methods for triglycerides in serum.
Authors: Kykstra S L , Lawrence J D
Published: January 2020

We compared three commercially available kits for use in determining triglycerides (triacylglycerols) in serum, by different methods, for accuracy and precision, with use of pooled sera of low, normal, and high triglyceride concentrations. Accuracy varied from -17% to +16% of the independently determined value, depending on the method and triglyceride concentration. In general, the Calbiochem method was the most nearly accurate, and only it met Center for Disease Control criteria for precision at all three triglyceride concentrations. The relationships of mean values to the suggested normal range for each method varied, some significant differences being found. Our data demonstrate the importance of a correlation between the independently determined value and the normal range for the method used and stresses the need for normal-range values to accompany all patients' reports.
Evaluation of enzyme-multiplied immunoassay technique (EMIT) for determination of serum digoxin.
Authors: Rosenthal A F , Vargas M G , Klass C S
Published: January 2020

Sixty-seven digoxin-containing sera were analyzed by both radioimmunoassay and EMIT. After some important modifications of the EMIT method, agreement between the two methods was very good. Reproducibility of the EMIT assay was excellent; daily variations in values found for control sera were quite small, and recovery of added digoxin was good. Slight hemolysis hadnegligible effects, but highly hemolyzed specimens gave low recoveries of digoxin.
More sensitive high-pressure liquid-chromatographic determiantion of theophylline in serum.
Authors: Adams R F , Vandemark F L , Schmidt G J
Published: January 2020

We present procedures for determining theophylline in 50 mul of serum. The drug is extracted into a small volume of solvent that contains an internal standard, 8-chlorotheophylline. The extract is Analyzed by isocratic reversedphase chromatography, with measurement of eluted theophylline at 273 nm. Day-to-day reproducibility within 5% is attainable for the concentration range 5--20 mg/liter. Other xanthines and related metabolites do not interfere. Sensitivity is 1 mg/liter. The correlation coefficient, when results by a spectrophotometric procedure were compared, was 0.989. Amobarbital, secobarbital, phenobarbital, and diphenylhydantoin do not interfere. Total analysis time for a single sample is 15 min.
Separation and quantitation of serum constituents associated with calcium by gel filtration.
Authors: Toffaletti J , Gitelman H J , Savory J
Published: January 2020

Gel filtration of serum by use of polyacrylamide beads (Biogel P-2) separates total colcium into four distinct peaks: an initial peak, corresponding to protein-bound calcium; a second peak containing the calcium complexes of citrate, phosphate, lactate, and sulfate; a third peak containing calcium bicarbonate; and a fourth peak or trough corresponding to the serum ionic calcium. An eluent containing (per liter) 140 mmol of sodium, 1.1o mmol of calcium, 0.50 mmol of magnesium, and 10 mmol of 2-([tris(hydroxymethyl)methyl]amino)ethanesulfonic acid(pH 7.40 at 37 degrees C) provides physiological conditions that determine the equilibria between these calcium components. Association constants determined under these conditions permit calculation of the expected concentration of the calcium complexes in each tube of eluent, and these concentrations closely correspond to the amount of bound calcium measured experimentally. The mean distribution of calcium in healthy individuals, as determined by this method, is (per liter): calcium protein, 1.00 mmol; calcium complexes, 0.31 mmol; and ionic calcium, 1.07 mmol.
Serum phospholipids determined without acid digestion.
Authors: Sandhu R S
Published: January 2020

A method for determination of phospholipids in serum is described that involves complexing intact phospholipids with chromogenic reagent, thus eliminating the need for acid digestion, which is a mandatory step in all the current procedures for phospholipid analysis. Inorganic phosphorus and other serum components do not interfere in the determination. Excellent agreement between results of this new procedure and the conventional acid digestion method (r=0.986, y intercept=2.053, and slope=0.986) makes it an attractive alternative clinical method for determination of phospholipids in serum.
Immunofixation. III. Application to the study of monoclonal proteins.
Authors: Ritchie R F , Smith R
Published: January 2020

We have shown how immunofixation can be successfully used to study proteins exhibiting electrophoretic polymorphism. An analogous situation is seen in the disorders of the immune system that result in the production of variable quantitites of homogeneous immunoglobulins. Immunoelectrophroesis has been heavily used--sometimes unsuccessfully because of poor resolution--to study these materials. The appearance of a monoclonal immunoglobulin band is identical in both immunofixation and standard gel electrophoresis, a feature that allows unambiguous identification of a protein as to its heavy-chain class and light-chain type. Because antigen and antibody are placed in contact almost immediately after electrophoresis, interfering diffusion does not occur and even extremely small bands can be demonstrated and characterized.
A spot test for uroporphyrinogen I synthase, the enzyme that is deficient in intermittent acute porphyria.
Authors: Schumaker H M , Tishler P V , Knighton D J
Published: January 2020

We describe a spot test for detecting deficiency of uroporphyrinogen I synthase (EC 4.3.1.8), which is characteristic of intermittent acute porphyria. The specimens used for enzyme assay are 6.5-mm filter paper discs saturated with dried blood (less than 15 mul) that was collected by direct application from a fingerstick or from venipuncture, with or without anticoagulant. The enzyme in such specimens is stable for at least nine days at -20 or c degrees C or for two days at room temperature. The discs are incubated with porphobilinogen (0.11 mmol/liter) in tris(hydroxymethyl)aminomethane HCl buffer, pH 8.2, in the dark at 37 degrees C for 3.5 h. Trichloroacetic acid is added and, after centrifugation, the supernate is examined visually with a long-wavelength ultraviolet lamp. Samples from normal and porphyric subjects are readily differentiated, both by color and intensity of the resulting porphyrin fluorescence. Anemia is a potential source of falsely positive tests, but one may accurately determine the concentration of hemoglobin in the whole blood on the filter paper discs. Moreover, the fluorescence of normal but anemic samples clearly differs qualitatively from that of porphyric specimens. Another source of falsely positive tests, variation in enzyme activity creating an overlap zone of normal and porphyric results, has not been a confounding problem. The method thus seems to offer promise for screening populations for this disorder.
Energy-dispersive x-ray fluorescence spectroscopy and inductively coupled plasma emission spectrometry evaluated for multielement analysis in complex biological matrices.
Authors: Irons R D , Schenk E A , Giauque R D
Published: January 2020

Energy-dispersive x-ray spectroscopy and inductively coupled plasma emission spectrometry were evaluated as methods for routine multielement analysis of biological material. Standard samples included Standard Reference Materials (National Bureau of Standards), compounded mixtures, and supplements that provided a wide range of elemental concentrations for analysis. Elements included in this study were Zn, Pb, Ni, Mn, Fe, Mg, Cu, Ca, As, Se, Br, Rb, and Sr. Standards were analyzed as unknowns by participating laboratories. The two methods were evaluated for sensitivity, precision, and accuracy, and the results compared to those obtained for atomic absorption spectrometric analysis of identical standard unknowns. Both methods compared favorably and both were determined to be highly reliable for such an application. Advantages and disadvantages of each method are compared and discussed.
Molar absorptivities of beta-NADH and beta-NADPH.
Authors: Ziegenhorn J , Senn M , Bücher T
Published: January 2020

Re-investigating the accuracy of the commonly used values for molar absorptivities (epsilon) of beta-NADH and beta-NADPH at Hg 334, Hg 365, or 340 nm, we obtained the following results: The maximum of absorbance of NADH is shifted from about 340 nm at 0 degrees C to about 338.5 nm at 38 degrees C; the corresponding maxima of NADPH are located at about 0.5-nm longer wavelengths. In addition, the absorption curves of both coenzymes broaden with increasing temperature. For these reasons, the epsilon-values of NADH and NADPH are generally different from each other, and are temperature-dependent. Only at 334 nm are they almost identical and nearly independent of temperature. Therefore this wavelength is recommended for precise measurements. The epsilon-values of these coenzymes are influenced by ionic strength and pH. To determine the absolute values of the molar absorptivities, we performed the glutamate dehydrogenase or lactate dehydrogenase assay with carefully purified 2-oxoglutaric acid or pyruvic acid in the presence of excess coenzyme. The purity of the substrates was checked through differential scanning calorimetry, moisture analysis, gas-liquid chromatography, gas chromatography in combination with mass spectrometry, and nuclear magnetic resonance spectroscopy. The epsilon-values observed under the various conditions are about 1-7% higher than those currently used.
Evaluation of two digoxin radioimmunoassay procedures in which 125I-labeled digoxin is used.
Authors: Kuczala Z J , Ahluwalia G S
Published: January 2020

We present a comparative evaluation of two commercial kits, the "Quantitope" and "GammaCoat," for radioimmunoassay of digoxin in serum. These kits, in which iodine-125 is used as a label, proved to suitable for digoxin assay as determined by their reproducibility, sensitivity, precision, and a regression analysis. Hemolysis, lipemia, and icterus did not affect results. However, in some cases hypoalbuminemia falsely lowered the assayed digoxin concentration. Recovery of pure digoxin added to native patients' sera having low albumin concentration (24-28 g/liter) ranged from 67-105% with the Quantitope kit and 70-110% with the GammaCoat kit. Low serum albumin concentration did not always decrease the recovery of digoxin; this effect varied from serum to serum, which may indicate that there are factors other than albumin that affect the assay of digoxin.
Rapid micromethod for blood lead analysis by anodic stripping voltammetry.
Authors: Morrell G , Giridhar G
Published: January 2020

We describe a rapid microscale procedure for blood lead determination by anodic stripping voltammetry. Results correlate well with those obtained by atomic absorption spectroscopy. The procedure involves use of a metal-exchange reagent, which rapidly releases bound lead from its macromolecular binding sites, thus eliminating a long and cumbersome perchloric acid digestion procedure. Reproducibility and analytical recovery of added lead were both excellent. Our results show that anodic stripping voltammetry is a reliable, sensitive micromethod for routine determination of blood lead.
Measurement of diphenylhydantoin in 0.1-ml plasma samples: gas chromatography and radioimmunoassay compared.
Authors: L'Estrange Orme M , Borgå O , Cook C E , Sjöqvist F
Published: January 2020

Concentrations of diphenylhydantoin in 364 plasma samples have been measured both by radioimmunoassay and with a recently developed gas-chromatographic method, which requires only 0.1 ml of plasma per determination. There was an excellent correlation between values obtained by the two methods (r = 0.986), and in only 11 plasma samples did the results differ by more than 20%. Of the investigated samples, 105 were obtained from uremic patients. For these, an equally good agreement was obtained between the two methods. Within-assay variance was 3.1% for the immunoassay and 3.3% for the gas-chromatographic procedure. Without automatic pipetting equipment, the radioimmunoassay procedure took twice as long as the chromatographic assay, and the cost of chemicals was considerably higher. Nevertheless, the better sensitivity of the radioimmunoassay makes it of great value, especially in children, because plasma samples of 10 to 20 mul can be used.