bluuebunny/crossref_metadata_2025 huggingface dataset:
Serum copper concentration and hepatic enzyme induction during long-term therapy with anticonvulsants.
Authors: Tutor J C , Fernandez M P , Paz J M
Published: January 2020

We evaluated hepatic enzyme induction by measuring urinary D-glucaric acid and serum gamma-glutamyltransferase in a group of 40 adult epileptics of both sexes who were receiving long-term treatment with phenobarbital and (or) phenytoin. Total concentrations of copper and ceruloplasmin in their serum and the oxidase activity of ceruloplasmin were significantly greater than in the control group. However, non-ceruloplasmin copper and specific oxidase activity of the ceruloplasmin (activity per gram) were unchanged. A highly significant relationship was found between gamma-glutamyltransferase and (a) copper (r = 0.682, p less than 0.001), (b) ceruloplasmin (r = 0.523, p congruent to 0.001), and (c) the oxidase activity of the ceruloplasmin (r = 0.598, p less than 0.001). There is also a significant correlation of hemopexin with ceruloplasmin (r = 0.531, p congruent to 0.001) and the oxidase activity of the ceruloplasmin (r = 0.598, p less than 0.001). These results suggest that hypercupremia in patients undergoing long-term anticonvulsant therapy is a direct result of hepatic enzyme induction caused by the drugs that induce synthesis of ceruloplasmin.
Homogeneous enzyme immunoassay for tobramycin evaluated and compared with a radioimmunoassay.
Authors: Woo J , Longley M A , Cannon D C
Published: January 2020

We evaluated a commercially available homogeneous enzyme immunoassay (EMIT, Syva Co.) for tobramycin against a reference radioimmunoassay (RIA) method. Between-assay precision (CV) was 2.9% at 6.2 mg/L and 3.0% for values in the range of 1.0-7.6 mg/L. Accuracy based on a recovery experiment (1.0-13.0 mg/L) yielded an analytical recovery of 88-112%. A correlation study with 75 sera from patients on tobramycin therapy showed that EMIT = 0.984 RIA - 0.0808, r = 0.993. Neither the EMIT nor the RIA procedure was affected by the presence of gentamicin, amikacin, and vancomycin. Absorbance data from the EMIT system calculated with the conventional RIA logit-log algorithm correlate well with results generated by the Syva data-handling system (logit-log = 1.077 Syva - 0.318, r = 0.998). A reagent stability study indicated that the EMIT reagents, once reconstituted, remain stable for at least 17 days when stored at refrigerated temperatures, or 11 days if stored at room temperature, thus enabling frequent "stat" assays without the need to prepare a calibration curve each time.
Liquid-chromatographic measurement of nitrazepam in plasma.
Authors: Kelly H , Huggett A , Dawling S
Published: January 2020

In this simple and rapid "high-performance" liquid-chromatographic method for determining nitrazepam in plasma, serum, or whole blood, the sample at pH 7.4 is extracted into diethyl ether with an internal standard (prazepam), chromatographed, and detected at 280 nm with a fixed-wavelength ultraviolet detector. A specimen, together with standards and a quality control, can be analyzed in duplicate within 90 min. The limit of sensitivity is 5 micrograms/L (nitrazepam and 7-acetamidonitrazepam) and 50 micrograms/L (7-aminonitrazepam), and no interferents have been found. This method has the advantages of a small sample requirement and complete resolution of nitrazepam and the above-mentioned major metabolites. We have used this method for analysis of therapeutic and overdose concentrations of nitrazepam, and to investigate the stability of the drug in blood.
Verapamil and calcium-stimulated enzyme efflux from skeletal muscle.
Authors: Anand R , Emery A E
Published: January 2020

An early and significant biochemical abnormality in Duchenne's muscular dystrophy is an increase in intracellular calcium. We have found that the "calcium-blocker" drug verapamil inhibits calcium-stimulated efflux of creatine kinase (EC 2.7.3.2) and lactate dehydrogenase (EC 1.1.1.27) in vitro from normal human skeletal muscle at therapeutic concentrations. Such a calcium blocker might therefore be useful in the treatment of Duchenne's muscular dystrophy.
Radioimmunoassay for phencyclidine (PCP) in serum.
Authors: Owens S M , Woodworth J , Mayersohn M
Published: January 2020

This accurate, sensitive radioimmunoassay for determining phencyclidine concentrations in serum specimens involves the use of anti-phencyclidine sera, 0.1 mL of serum specimen, an iodinated tracer, and a solid-phase separation. Phencyclidine metabolites do not show significant cross reactivity, but several phencyclidine analogs do cross react. Within-run coefficients of variation for human and dog serum ranged from 2.5 to 13% for concentrations from 2.0 to 500 micrograms/L. Day-to-day coefficients of variation for human and dog serum ranged from 4.3 to 16.7% for concentrations ranging from 2.0 to 90.0 micrograms/L. The sensitivity of the radioimmunoassay is less than 0.5 micrograms/L. Thirty serum specimens from two dogs given 1 mg of phencyclidine per kilogram body weight were analyzed by radioimmunoassay and a gas-chromatographic method. Nonparametric statistical comparison and linear regression showed that results from the two procedures correlate well (r2 = 0.952). Concentration-time data from the two dogs are presented to illustrate the utility of the radioimmunoassay for examining phencyclidine disposition.
Unpredictable fluctuations in transcutaneous pCO2 from capillary blood gas determinations.
Authors: Kost G J , Chow J L , Kenny M
Published: January 2020

Transcutaneous pCO2 electrode response time was optimized by use of a new electrode filling solution composed of NaCl/NaHCO3 electrolyte buffer (100 and 20 mmol/L, respectively) in an equivolume mixture of glycerol and water. The 95% response time to a step change in pCO2 was 49.9 +/- 2.8 s (mean +/- SD) when there was no spacer between the membrane and glass of the electrode. Use of this filling solution during monitoring of severely ill premature infants with cardiopulmonary disease allowed identification of large, unpredictable transient changes in transcutaneous pCO2, and therefore presumably in arterial pCO2, that occurred during capillary blood gas sampling. The changes, which occurred in 19 of 20 samplings, ranged from -1.06 + 2.53 kPa (-8 to +19 Torr). The maximum relative change observed was +29%. These results indicate that the standard protocol for capillary blood collection induces significant transient fluctuations in blood gas tensions. We believe these fluctuations decrease the reliability of capillary pCO2 values for use in clinical management in patient populations similar to ours.
Urinary enzyme excretion by renal-transplant recipients in relation to interval after transplantation.
Authors: Jung K , Diego J , Scholz D , Schröder K , Strobelt V
Published: January 2020

We determined the urinary excretion of the enzymes aminopeptidase (EC 3.4.11.2), alkaline phosphatase (EC 3.1.3.1), gamma-glutamyltransferase (EC 2.3.2.2), and N-acetyl-beta-glucosaminidase (EC 3.2.1.30) in two groups of renal-transplant recipients at different times after transplantation (1.8 months and 52 months, respectively). Both groups of patients showed a higher rate of enzyme excretion than did a reference group of healthy persons. More aminopeptidase and N-acetyl-beta-glucosaminidase were excreted during the early period after transplantation than later. The time-dependence of urinary enzyme excretion was confirmed in six renal-transplant recipients studied during the course of 15 months after transplantation. There was a general correlation between the extent of urinary enzyme excretion and both the time after transplantation and the daily dose of prednisolone. Therefore, it is necessary to take into account this influence on the extent of urinary enzyme in renal-transplant recipients if urinary enzyme excretion is used as an indicator of renal disorder and especially as an early predictor of transplant rejection.
Release tags: a new class of analytical reagents.
Authors: Joppich-Kuhn R , Joppich M , Giese R W
Published: January 2020

Release tags are novel compounds made up of three molecular groups: "signal," "release," and "reactivity." The signal group is the detected part of the tag, the release group provides a site for specific covalent cleavage, and the reactivity group attaches the tag to a substance of interest. The general purpose of release tags is to function as molecular labels, analogous to radioisotopes. Release tags also extend the applicability of gas-phase electrophores as signal groups to the analysis of nonvolatile substances. These electrophores are measured with high sensitivity and specificity by gas chromatography with electron-capture detection (GC-ECD). Because extensive multiplicity is potentially available with GC-ECD electrophores, many analogous but distinctive release tags can be used simultaneously as labels in a given assay. In this paper, we use N-pentafluorobenzoylmethionylglycine-N-hydroxysuccinimide ester, our first GC-ECD release tag, to determine thyroxin in serum by a method called "labeling analysis," which involves the principle of isotope-derivative analysis.
A short-term in vitro drug-screening assay for cancer chemotherapy.
Authors: Chen S L , Snoga J R , Croft H
Published: January 2020

In this short-term in vitro assay for detection of tumor cell sensitivity to drugs, we have replaced the traditional soft-agar colony-forming assay with the measurement of DNA synthesis, to determine the cell renewal capability of the tumor cell population. The tumor cells are treated with drugs and cultured for five days. During the last 12--18 h of culture the cells are pulsed with [3H]thymidine, then harvested for scintillation counting. The effects of drugs are expressed as the percentage of DNA synthesis as compared with that of the control. When the % DNA synthesis is less than 40%, the drug is considered to be effective. So far we have studied tumor cells from multiple myeloma, non-Hodgkin's lymphoma, and carcinoma of lung, breast, ovary, stomach, and bladder. The overall negative predictive value is 1.0. The results are available within five days, compared with 21--28 days for completion of soft-agar assays; fewer cells are required; and the process is semiautomated.
Development of a multichannel electrochemical centrifugal analyzer.
Authors: Cho H K , Lee Y H , Couch R A , Jagadeesh J M , Olson C L
Published: January 2020

A new instrument has been developed that is similar in design and concept to the GeMSAEC centrifugal analyzer (Oak Ridge National Laboratory) except that electrochemical detection is used rather than optical detection. The present version has eight channels, each with its own detector. Problems of speed control and sampling synchronization are greatly minimized from those of a multichannel centrifugal analyzer having a single detector system. All eight sample compartments and polarographic cells are contained in a single Teflon rotor, 7.7 cm in diameter. The working electrodes are planar carbon electrodes. The initial application of the analyzer is in kinetic methods involving the rates of enzyme-catalyzed reactions. The initial system chosen was the glucose oxidase system. When the rotor is spun, the solution moves into the sample cell and up against the planar working electrode. The reaction starts and current is measured as a function of time at a constant applied voltage. The current output from each polarographic circuit is connected to a separate channel of a multiplexed analog-to-digital converter. The analyzer is controlled by a dedicated microcomputer system, which sets the polarographic cell voltages, collects the current-time data, and calculates the results.
An electrochemical assay system for peroxidase and peroxidase-couplers reactions based on a fluoride ion-selective electrode.
Authors: Siddiqi I W
Published: January 2020

A sensitive and accurate potentiometric reaction-rate method for the assay of peroxidase (EC 1.11.1.7) and peroxidase-coupled reactions is described. The technique is based on the peroxidase-catalyzed rupture of the covalent C--F bond in certain organo-fluoro compounds in the presence of H2O2 and the measurement of liberated F- by a fluoride ion-selective electrode. In a study screening 26 organo-fluoro compounds, 12 were susceptible to C--F bond rupture. However, analytically useful reaction kinetics were observed only with 4-fluoroaniline, 5-fluor-2-methylaniline, 4-fluorophenol, 2,3,5,6-tetrafluorophenol, pentafluorophenol, and 3-fluoro-DL-tyrosine. With this assay system, peroxidase activity as low as 25 mU/L could be precisely measured within 2 min. The reaction was coupled to glucose oxidase and cholesterol oxidase for the determination of glucose and cholesterol. Glucose oxidase activity in solution (to 2 U/L) was measured to demonstrate the feasibility of the assay for oxidase enzymes. Only a few microliters of sample is required and most determinations can be completed within minutes. The assay system offers broad applications and is especially attractive for use in enzyme immunoassays.
Statistical comparison of blood glucose as determined by several test-strip procedures and by a hexokinase procedure.
Authors: Stewart T C , Kleyle R M
Published: January 2020

We report a new statistical tool for comparing several dry-reagent strip procedures for whole blood glucose, which produce data in both digital and ordinal form, with results by the well-studied hexokinase-glucose-6-phosphate dehydrogenase procedure coupled to NAD+-NADH. Our use of "ordinal comparison unit" allows for a more equitable comparison of such data. These strip procedures produce biases of -2.21 to 1.74 ordinal comparison units over the range of glucose values corresponding to hypoglycemia and hyperglycemia, as compared with results by the hexokinase procedure, but they are essentially equivalent when compared with each other.
Improved enzymatic determination of total cholesterol in tissues.
Authors: Cho B H
Published: January 2020

In this improved method for rapid enzymatic determination of total cholesterol, the lipid extracts from tissues are dissolved in an equal volume of peroxide-free dioxane/isopropanol (50/50 by vol) solution, and are reacted directly with the aqueous enzymatic reagent, without further treatment. The presence of organic solvents, such as dioxane and isopropanol, does not interfere with enzymatic activity. This simpler procedure eliminates the tedious solubilization of tissue lipid extracts into an aqueous medium. The method is reproducible, and results correlate well with those by a chemical (FeCl3/H2SO4) method.
Comparison of amniotic fluid alpha-fetoprotein reactivity to Lens culinaris agglutinin and concanavalin A in crossed-affinity immunoelectrophoresis: ancillary tests in the prenatal diagnosis of severe fetal malformations.
Authors: Toftager-Larsen K , Kjaersgaard E , Nørgaard-Pedersen B
Published: January 2020

Crossed-affinity immunoelectrophoresis of alpha-fetoprotein in amniotic fluid from 135 normal and 39 abnormal pregnancies (mainly neural-tube defects) was performed with a lectin, agglutinin from Lens culinaris. Results were compared with findings reported for another lectin, concanavalin A. Three fractions of alpha-fetoprotein were obtained by reaction with Lens culinaris agglutinin. The most weakly reactive fraction correlated strongly with the concanavalin A nonreactive fraction. With both lectins, significantly lower concentrations of these fractions were found in all samples from abnormal pregnancies than in those from normal pregnancies. In eight cases with a fetal abnormality the total alpha-fetoprotein concentrations were below the lower limit for abnormal samples. All eight samples revealed fractions weakly reactive with Lens culinaris agglutinin below the lower 0.1% limit for normal samples; seven of these samples had fractions nonreactive with concanavalin A below this limit. Although a decrease in the two described fractions in normal pregnancies was found with increasing gestational age, we find either method to be valuable as an ancillary test in the prenatal diagnosis of fetal neural-tube defects and other malformations.
Unpredictable error in calculated bicarbonate homeostasis during pediatric intensive care: the delusion of fixed pK'.
Authors: Rosan R C , Enlander D , Ellis J
Published: January 2020

Bicarbonate balance is usually calculated from indirect total CO2 values determined by blood-gas analysis. Total CO2 is computed from the Henderson-Hasselbalch equation, under the assumption that the pK' is constant or at most varies insignificantly. In pediatric patients in intensive care, we have found instances of large errors in this assumption. We join Natelson and Nobel in asserting that total CO2 should be measured. Little reliance should be placed on bicarbonate estimation.
An immunoradiometric assay for erythrocyte complement (C3b) receptor activity applied to a pediatric population with connective tissue disease.
Authors: Buffone G J , Leatherwood C M , Person D A , Brewer E J
Published: January 2020

The number of receptors for complement component C3b per erythrocyte reportedly is decreased in over half of adults with systemic lupus erythematosus. We have devised an immunoradiometric assay for C3b receptor (CR1) on erythrocytes, with which one can assess CR1 saturation due to in vivo binding of immune complexes or activated complement fragments (C3b). Using this assay, we examined binding by CR1 in normal adults and newborns, in lupus and juvenile rheumatoid arthritis patients, and in a population of patients with various general medical problems, including other connective tissue diseases. Binding by CR1 was decreased in eight of 15 SLE patients, four of 25 juvenile rheumatoid arthritis patients, and one of 14 patients with other diseases. We found no significant correlation between CR1 binding and either C1q binding, antinuclear antibody titer, results for complement C3 and C4, or the presence of renal disease. Using this assay, we were also able to show that the observed reduction in CR1 binding was not ascribable to prior saturation of CR1 or to blocking antibody against CR1. The assay is precise and easy enough for routine application.
Comparison of a commercially available assay system with two reference methods for the determination of plasma cholinesterase variants.
Authors: Whittaker M , Britten J J , Dawson P J
Published: January 2020

For assaying plasma cholinesterase (EC 3.1.1.8) activity and phenotyping by means of dibucaine inhibition, we have compared a commercially available kit, in which butyrylthiocholine is used as substrate, with two reference methods, one using benzoylcholine and the other propionylthiocholine. With 50 different samples of three of the most common genetic variants, we could clearly differentiate the variants with benzoylcholine and dibucaine, whereas there was some overlap of the E1uE1u and E1uE1a phenotypes with the other two substrates at 30 degrees C. The phenotypes were better differentiated at 25 degrees C, and in our hands the use of butyrylthiocholine was preferable to propionylthiocholine for phenotyping with dibucaine. The affinity of the usual and atypical homozygotes for fluoride with butyrylthiocholine gave an inverted response to the affinity of these variants for the anion with benzoylcholine. We suggest that this may be explained by the role of the chromogen or its products in the assay procedure with the thiocholine substrate.
Time-resolved fluoroimmunoassay of human pancreatic phospholipase A2.
Authors: Eskola J U , Nevalainen T J , Lövgren T N
Published: January 2020

We describe an immunofluorometric assay for human pancreatic phospholipase A2 based on time-resolved fluorescence. The labeled antibody technique in combination with the time-resolved 1-s fluorometric detection of the europium label, which essentially eliminates all background fluorescence, resulted in a high sensitivity (20 ng/L) and a wide (5000-fold) linear range. Nonspecific binding was minimized by treating the solid-phase antibody with NaSCN before coating, to remove endogenous antigen, and by immunosorbent purification of the antibody before labeling with europium. This is a one-incubation, multi-site, solid-phase assay on polystyrene microtiter strips, even though a polyclonal antibody was used. As measured by this assay, activity of immunoreactive phospholipase A2 was found to be above normal in sera of patients suffering from acute pancreatitis.
Electroimmunoassay of albumin in human serum: accuracy and long-term precision.
Authors: Pascucci M W , Grisley D W , Rand R N
Published: January 2020

An improved procedure for the Laurell "rocket" technique is described. Samples were electrophoresed in an agarose gel containing anti-human albumin. The gel plates were processed, the peaks stained, and peak heights used to calculate albumin concentrations. Factors affecting precision were (a) adequate heating of agarose gel before antibody is added, (b) accurate leveling of the gel surface during plate formation, (c) applied voltage during sample application, and (d) avoidance of the "edge" effect on sample placement in the gel. Multi-plate long-term precision (CV) for the method was 6.2% at a mean albumin concentration of 13 g/L and 3.0% at 37 g/L. Analytical recovery of 8 and 11 g of albumin per liter was 99 to 100%. There was negligible interference from hemoglobin and dextran as well as several common substances that bind to albumin--bilirubin and salicylate. Because of its high accuracy and good long-term precision, the method is a possible candidate reference method for serum albumin.
Direct measurement of testosterone in a pediatric center, with use of a radioimmunoassay kit and unextracted serum.
Authors: Funderburgh L J , Zipf W B , Sotos J F
Published: January 2020

We evaluated a commercial (Radioassay Systems) radioimmunoassay kit for testosterone in which a double-antibody method and an 125I tracer are used. The 50-microL serum sample is assayed directly with no pre-extraction step. The assay system has good sensitivity (0.01 microgram/L), good precision (CV 5.2%), and little cross reactivity between testosterone and other androgens. Results compared well with those by a tritiated radioimmunoassay involving extraction (r = 0.98). Values obtained for 97 children compared well with published pediatric normal values. Evidently, this kit provides a rapid and reliable measurement of testosterone in serum specimens and is acceptable for use with pediatric patients.
24,25-dihydroxyvitamin D3 in serum: sample purification with Sep-Pak C-18 cartridges and liquid chromatography before protein-binding assay.
Authors: Traba M L , Babé M , de la Piedra C , Marín A
Published: January 2020

We describe a precise, specific method for measuring 24,25-dihydroxyvitamin D3 in human serum. A 2-mL serum sample is extracted with acetonitrile and passed through a Sep-Pak C-18 cartridge. The sample is further purified by "high-performance" liquid chromatography under isocratic conditions on a normal-phase column (Radial-Pak silica-gel cartridge), then subjected to a protein-binding assay. The mean concentration of 24,25-dihydroxyvitamin D3 in serum from 22 normal adults (measured during the spring) was 2.9 micrograms/L (SD 1.9, range 6.3-0.42 microgram/L). The intra-assay CV was 7.7%, the interassay CV 11.2%. Purification of the sample with Sep-Pak C-18 and liquid chromatography on normal plus reversed-phase columns leads to a mean value of 3.4 micrograms/L (SD 1.6 micrograms/L, n = 12), not significantly different from results with our method.
Evidence for interference by ascorbate in the measurement of cerebrospinal fluid glucose by a kinetic glucose oxidase/peroxidase procedure.
Authors: Maguire G A , Price C P
Published: January 2020

Glucose in the cerebrospinal fluid (CSF) of neonates, as measured with a kinetic glucose oxidase/peroxidase procedure, was sometimes very low. When these samples were stored at 4 degrees C and subsequently re-analyzed, or if the samples were analyzed at any time after receipt by using a glucose dehydrogenase assay, the values were much higher. We found that the discrepancies in the values were caused by a lag phase in the kinetic method, during which no color developed. Because the lag phase exceeds the time over which the reaction is monitored in the kinetic procedure, this leads to the erroneously low values. The interference could be reproduced experimentally by adding ascorbic acid to CSF or plasma samples, or removed by adding ascorbate oxidase to CSF samples. Plasma glucose, as estimated by the kinetic glucose oxidase method, showed no such interference.
An evaluation of 10 kits for determination of human choriogonadotropin in serum.
Authors: Rasor J L , Farber S , Braunstein G D
Published: January 2020

We compared 10 commercially available radioimmunoassay kits (American Diagnostics, Becton Dickinson, BioGenex, Clinical Assays, Hybritech, Leeco, Mallinckrodt, Microanalytic, Nuclear Medical Systems, and Radioassay Systems) for determination of human choriogonadotropin (hCG), using serum pools, hCG CR119 (NIH), 2nd I.S. (who), and 1st I.R.P. (who). Criteria were ease of performance, total assay time, sensitivity, potency, and parallelism as compared with reference standards and results for 15 serum pools. The Mallinckrodt kit exhibited the best overall performance, with good low-concentration sensitivity, parallelism with two of the three reference preparations, and good clinical correlation as compared with the reference kit from NIH. Because the antibodies used in the kits are occasionally changed by the manufacturers, these results are necessarily valid only for kits that include reagents identical to those in the kits that we tested.
Liquid-chromatographic determination of alpha- and gamma-tocopherols in erythrocytes, with fluorescence detection.
Authors: Lehmann J , Martin H L
Published: January 2020

We have adapted to erythrocytes a method for the determination of alpha- and gamma-tocopherols in plasma and platelets. Erythrocytes (50 microL) were extracted with methanol containing tocol (internal standard) and pyrogallol. Tocopherols were partitioned into chloroform, washed, and injected in methanol onto a reversed-phase (C18) "high-performance" liquid-chromatographic column. The mobile phase was methanol/water (99/1 by vol) at a flow rate of 2 mL/min and detection was with a "high-performance" spectrophotofluorometer. The limit of detection for either tocopherol is 0.10 microgram/mL of packed cells. Analytical recoveries ranged from 93 to 104%. Some values for tocopherols in human erythrocytes are presented.
A unique protein in normal human cerebrospinal fluid.
Authors: Papadopoulos N M , LeWitt P A , Newman R P , Raphaelson M I , Chase T N
Published: January 2020

On analysis of cerebrospinal fluid (CSF) samples from normal volunteer donors by high-resolution zone electrophoresis on agarose gel, an electrophoretically homogeneous protein band consistently appeared in the gamma-globulin region. Application of immunofixation electrophoresis in attempts to identify the band with use of monospecific antibodies against individual human serum proteins and against heavy- and light-chain immunoglobulins as well as polyvalent antisera did not produce a positive immunoprecipitation reaction with the protein band. The serum samples from these subjects did not show similar bands. Therefore, we conclude that this protein band is a normally occurring protein that is unique to CSF.
Monoclonal antibodies to human plasma low-density lipoproteins. II. Evaluation for use in radioimmunoassay for apolipoprotein B in patients with coronary artery disease.
Authors: Patton J G , Badimon J J , Mao S J
Published: January 2020

We describe the importance of the low-density lipoproteins (LDL) used in preparing radioimmunoassay standard curves and the clinical application of monoclonal antibodies to LDL. LDL isolated from five normal men produced five parallel displacement curves with conventional mouse antiserum but there was a significant difference of immunoreactivity among the LDL. None of our four monoclonal antibodies could eliminate the heterogeneous immunoreactivity of different LDL. Thus, the determination of plasma apolipoprotein (apo) B will vary depending on the selection of LDL standards, and the comparison of absolute apo B values between laboratories will be of questionable value unless they use the same LDL standard. Nonetheless, in a radioimmunoassay our monoclonal antibody, LP-22, detected a more significant (p less than 0.0001) increase of plasma apo B in patients with angiographically documented coronary artery disease than did conventional antiserum (p less than 0.001). In addition, the overlap of apo B concentrations for patients with and without disease was less when monoclonal antibody LP-22 was used. We conclude that patients with coronary artery disease have a significant increase in the form of plasma apo B that is specifically recognized by LP-22 monoclonal antibody. Perhaps monoclonal antibodies will be able to sort out the various components of apo B, delineate their possible atherogenic roles, and offer us a predictive value for diagnosing such patients.
Effect of short-term storage conditions on alcohol concentrations in blood from living human subjects.
Authors: Winek C L , Paul L J
Published: January 2020

We examined the effects of time, temperature, and a preservative (sodium fluoride) on ethanol concentrations in stored samples of whole blood from living human subjects. We measured the ethanol in the first, second, seventh, and 14th day of storage, by gas chromatography. Samples were stored at 0-3 degrees C and at 22-29 degrees C, with and without preservative. None of these showed significant gains or losses in concentration. The average differences between ethanol as measured on the day of collection and after storage were all within the range of experimental error of the method (+/- 5%).
Evaluation of a solid-phase enzyme immunoassay for human choriogonadotropin beta subunit.
Authors: Davey D D , Sample M M , Oei T O
Published: January 2020

We evaluated a quantitative solid-phase enzyme immunoassay for human choriogonadotropin beta subunit (beta-HCG) with anti-beta-HCG:horseradish peroxidase conjugate, recently marketed by Abbott Laboratories. We compared results on 56 patients' serum specimens, obtained mostly for followup of neoplastic disease, with those by a competitive radioimmunoassay kit. The correlation was good, the differences being of little clinical significance. Linear regression in the low and intermediate ranges gave a slope of 0.93, a y-intercept of 0.34, and a correlation coefficient of 0.97. Precision studies yielded an interassay CV of 6.4% in the intermediate range and 13% in the low range. Sensitivity was 0.69 int. unit/L. Cross reactivity was 1 to 2% with specimens fortified with lutropin or follitropin. The only substantial problem was with linearity in the upper part of the standard curve, especially in the interval, 100-200 int. units/L. This problem is obviated by adequate sample dilution.
Assay of urinary oxalate: six methodologies compared.
Authors: Zerwekh J E , Drake E , Gregory J , Griffith D , Hofmann A F , Menon M , Pak C Y
Published: January 2020

To assess how well results by different methods for urinary oxalate determinations agree with each other in a clinical setting, we compared six different assays: Hodgkinson and Williams (Clin Chim Acta 36:127-132, 1972), enzymatic, modified Hodgkinson and Williams, gas chromatography, ion chromatography, and "high-pressure" liquid chromatography. For the entire group of samples, the mean value by each method agreed relatively closely, although the enzymatic procedure produced a somewhat higher value. All six methods had large coefficients of variation within (8-58%) and between (15-88%) assays. In addition, analytical recovery by most assays was more than 100% of the added oxalate. Analytical recovery of 10 micrograms of oxalate added per milliliter of urine specimen ranged from 86 to 237%; for 20 micrograms/mL it was 83 to 320%. Thus for the six methods evaluated, no single method appeared to be superior to the others.
Changes in serum iron and leukocyte count associated with open-heart surgery.
Authors: Fitzsimons E J , Ballantyne G H
Published: January 2020

Rapid and pronounced changes in serum iron concentration and leukocyte count in association with open-heart surgery were observed in each of 58 patients. We examined the temporal aspects of these alterations. An initial increase in Fe concentration from a mean of 0.94 mg/L before surgery to 1.20 mg/L was observed within 6 h of the start of surgery. Decreased Fe concentration, a phenomenon previously associated with physiologically stressful events, became apparent 12 h after surgery, by which time the mean Fe concentration had declined to 0.26 mg/L. An increase in the mean leukocyte count, from 7.1 to 15.2 X 1000/mm3 was observed within 6 h of the start of surgery. An increase in ferritin concentration in serum was concurrent with decreased iron concentration.
Spectrophotometry of occult blood in feces.
Authors: Welch C L , Young D S
Published: January 2020

This method for measuring fecal occult blood is based on the heme-catalyzed oxidation of tetramethylbenzidine by H2O2. An aliquot of heated stool homogenate is mixed with acetic acid to chemically separate heme from globin. The heme is extracted into ethyl acetate and reacted with the reagent and H2O2 to produce a green oxidation product. The reaction is followed kinetically for 30 to 60 s at 660 nm. A660 is linearly related to the amount of hemoglobin. The lower limit of detection is 1 to 2 mg of hemoglobin per gram (wet weight) of feces. Within-day precision (CV) of the analysis for hemoglobin added to stool specimens (4 to 30 mg/g) ranged from 2.3 to 7.6%, between-day CV from 2.1 to 8.1%. Analytical recovery of hemoglobin added to fecal specimens (4 to 30 mg/g) ranged from 86.7 to 106.2%. Of the substances known to interfere with conventional dye-oxidation tests for fecal occult blood, only myoglobin and ascorbic acid interfere with hemoglobin quantification by our procedure. The test is fast, inexpensive, and easy to perform, and involves equipment available in hospital laboratories.
Interference with carcinoembryonic antigen radioimmunoassays by glycosaminoglycans, and their removal.
Authors: Wu J T , Mau E , Knight J A
Published: January 2020

Using the reagents from the CEA-Roche kit, we found that solutions containing only glycosaminoglycans (GAG) yielded false concentrations of carcinoembryonic antigen (CEA), and mixtures of CEA and GAG produced falsely high values. On the other hand, solutions of GAG yielded no additional CEA concentration when reagents from the Abbott CEA kit were used; rather, the CEA result was decreased with the Abbott kit for a CEA solution also containing GAG. These effects of GAG were not ascribable to contamination, because neither gel filtration nor ion-exchange column chromatography separated the false Roche CEA content related to GAG from their peaks of uronic acid or from their anticoagulant activity. In addition, an enzyme specific for GAG eliminated these GAG-derived false concentrations. Both the positive and negative effects are correlated with concentrations of GAG. We found that the concentration of GAG could be decreased in a solution containing plasma proteins by either heating (70 degrees C, 15 min) or treating with perchloric acid (0.6 mol/L). The former is superior because essentially all GAG added to a solution containing plasma proteins were removed by heat, whereas as much as 25% to 80% of the GAG still remained after acid treatment. The effect of GAG was also completely eliminated by treating the specimens with chondroitinase ABC lyase (EC 4.2.2.4).
Preliminary isolation of urinary placental estriol before gas or liquid chromatography.
Authors: Andreolini F , Di Corcia A , Laganà A , Samperi R , Raponi G
Published: January 2020

We describe a rapid, simple assay for placental estriol in urine, involving a small sample volume (250 microL) and, correspondingly, a small amount of enzyme reagent. After hydrolysis, estriol is adsorbed from urine onto graphitized carbon black (Carbopack B). After some washing steps, estriol is desorbed with a small volume of a suitable mobile phase. This single-step purification technique is rapid (about 15 min), with minimal sample manipulation. Analytical recoveries for estriol-supplemented urine ranged from 95.9 to 101.0%. Ten replicate analyses of urines containing typical concentrations of estriol gave CVs of 3.3, 2.6, and 2.4% for low, medium, and high concentrations, respectively. The specificity of our extraction technique was good, as assessed by treating 35 urine samples and quantifying estriol by gas chromatography with packed and capillary columns and by liquid chromatography with ultraviolet and fluorometric detection.
Absorbance nephelometry of C1q-precipitable immune complexes: method comparisons and clinical correlations.
Authors: Levinson S S , Goldman J
Published: January 2020

Using a double-beam spectrophotometer, we investigated the clinical utility of a nephelometric method for assaying immune complexes. The complexes were concentrated from serum by precipitation with polyethylene glycol (PEG) and assayed by reaction with C1q. Testing of more than 100 sera showed a Spearman's rank correlation (p) between the present assay and the C1q-binding assay of 0.57, and 0.39 between the Raji cell assay and the present assay. Clinical sensitivity of the methods was not statistically different (p less than or equal to 0.5). Twenty-four of 30 patients with symptoms of disease showed increased concentrations of immune complexes by the present assay; only one of 38 normal individuals showed an increase. In a longitudinal study, we found that the concentrations of immune complexes paralleled clinical changes, indicating good clinical utility. The use of this assay with single-beam analyzers is limited because of the poor aqueous solubility of the PEG precipitate. Ongoing investigations designed to circumvent this problem are described.
Micro-analysis for quinidine in serum by thin-layer chromatography followed by fluorescence densitometry.
Authors: Kelner M , Bailey D N
Published: January 2020

We report a thin-layer-chromatographic micro-analysis for quinidine in serum, with detection by fluorescence densitometry. Quinidine is extracted from 20 microL of serum at pH 13 into 3 mL of hexane/acetone solution (80/20 by vol) containing N-(1-naphthyl)ethylenediamine as internal standard. The extract is concentrated and applied to silica-gel-impregnated plates for conventional thin-layer chromatography. Quinidine is identified from its RF value and quantified from the peak-height ratio between quinidine and the internal standard, relative to that of simultaneously extracted serum standards. The proposed assay is sensitive (to 0.2 mg/L), specific for unmetabolized quinidine, precise (between-run coefficients of variation less than 6%), and readily adaptable to large-scale "batch" analysis. Peak-height ratio is linearly related to concentration to at least 20 mg/L. Quinidine concentrations in the serum of patients, as measured by the proposed method (x) and by a traditional double-extraction spectrofluorometric assay (y), were related as follows: y = 0.994x + 0.276 (r = 0.989, n = 20).
Limited usefulness of the proportion of tests with normal results in review of diagnostic services utilization.
Authors: Eisenberg J M , Williams S V
Published: January 2020

We tested the hypothesis that the proportion of normal results in tests ordered by a physician correlates directly with the proportion of tests that are disapproved by a utilization review audit for inappropriate test use. Auditors reviewed 3497 charts for 13 067 repeated determinations of 10 diagnostic tests ordered by 81 medical residents to determine if test use had been appropriate, according to explicit criteria. By the Pearson product-moment correlation coefficient, there was a significant (p less than 0.001) correlation between the proportion of normal results in tests ordered by residents and the residents' audit-disapproval rates, a previously undocumented relationship. Although statistically significant, the correlation coefficient of 0.25 means that the proportion of normal tests results predicted only 6% of the variance in the audit-disapproval rates. This relationship is not strong enough to use the proportion of normal results as a measure of a physician's inappropriate test use, except to select physicians for utilization review.
Diagnostic efficacy of newer synthetic-substrates methods for assessing coagulation variables: a critical overview.
Authors: Fareed J , Messmore H L , Walenga J M , Bermes E W
Published: January 2020

With the introduction of synthetic substrates, many newer methods have been developed for testing coagulation parameters. Some of these methods are used in clinical settings, and many have been evaluated for their diagnostic efficacy in various coagulation disorders. Clinical chemistry laboratory instrumentation has been used to accommodate these methods. Commercially available kits for antithrombin III, heparin, plasminogen, alpha 2-antiplasmin, and factor X are used by many laboratories. Individual reagents have also become available and are being used to develop assays for routine diagnostic use. The development of suitable standards is rapidly underway, and their availability will facilitate adoption of these methods by hospital laboratories. Many of the synthetic-substrate-based assays that have been introduced for routine diagnostic purposes have been published recently. Here, we provide an overview of the newer amidolytic methods for the measurement of certain coagulation variables.
Inborn errors of steroid biosynthesis: detection by a new mass-spectrometric method.
Authors: Shackleton C H
Published: January 2020

A new mass-spectrometric technique relies on ionization during bombardment of the analyte (dissolved in a liquid matrix, usually glycerol) by an atom beam (e.g., Ar0, Xe0). This technique, termed "fast atom bombardment," is particularly useful in the characterization of polar charged molecules. A neutral beam is not essential, and a primary beam of cesium ions has been successfully used to produce spectra equivalent to those obtained by fast atom bombardment. In this communication I report data on the use of both ion and atom primary beams for producing secondary-ion mass spectra of conjugated steroids. In negative-ion spectra produced for steroid glucuronides and sulfates, the ion [M - H]- is invariably the major high-mass peak, and the lack of substantial fragmentation allows assay of relatively complex mixtures if the analytes differ in mass. I describe here the use of secondary-ion mass spectrometry for distinguishing, by urinary steroid analysis, patients with the four enzyme defects that can affect cortisol synthesis: defects in 17 alpha-hydroxylase, 3 beta-hydroxysteroid dehydrogenase/isomerase, 21-hydroxylase, and 11 beta-hydroxylase.
Assessment of the benzethonium chloride method for routine determination of protein in cerebrospinal fluid and urine.
Authors: Flachaire E , Damour O , Bienvenu J , Aouiti T , Later R
Published: January 2020

We have tested the characteristics of the method of Iwata and Nishikaze (Clin Chem 25: 1317, 1979). The linearity, sensitivity, and precision are satisfactory and the reactivity of benzethonium chloride with various proteins (albumin, immunoglobulins) is the same. The method has been compared with Meulemans's technique (Clin Chim Acta 5: 757, 1960), routinely used in our laboratories, by analysis of 82 samples of cerebrospinal fluid (CSF) and 119 samples of urine. Our results for cerebrospinal fluid agree well with those of Iwata and Nishikaze (r = 0.976; y = 0.992x - 0.013), but we find their method unsuitable for urinary protein determination, probably because of interfering compounds in urine.
Enzyme immunoassay for urinary albumin.
Authors: Fielding B A , Price D A , Houlton C A
Published: January 2020

We describe an enzyme-linked immunosorbent assay for urinary albumin, performed on microtiter plates with use of commercially available antisera and peroxidase conjugate. The assay range is 3-1000 micrograms/L, the sensitivity 625 pg. The method is suitable for measurement of albumin excretion in either normal or pathological urine. For 20 normal children, the range of urinary albumin excretion was 1.7-22.9 mg/24 h.
Ion-chromatographic measurement of oxalate in unprocessed urine.
Authors: Menon M , Mahle C J
Published: January 2020

We describe a sensitive, simple technique for determining urinary oxalate. Urine, diluted as necessary with distilled water, is injected into an ion chromatograph. Oxalate is detected conductimetrically as a distinct peak near the tail of the chromatogram. This peak specifically represents oxalate, because it is abolished if the sample is treated with oxalate decarboxylase. We have used this technique to measure oxalate in more than 3000 consecutively received urine samples. It has a CV of 6%.
Immunoglobulin-complexed aspartate aminotransferase.
Authors: Weidner N , Lott J A , Yale V D , Wahl R L , Little R A
Published: January 2020

We report two cases of unexplained, isolated, persistently increased aspartate aminotransferase activity in serum. In the first patient, this lasted for 10 years and prompted multiple hospitalizations and medical/surgical consultations. For patient two, the abnormal enzyme activity resulted in hospitalization for further evaluation of possible heart disease. In spite of extensive investigation to determine the possible reason for the abnormality, no clear clinical cause was ever discovered in either patient. Electrophoretic and immunologic evidence indicates that the enzyme was complexed to IgG in the serum of both individuals. Recognition that this complex is probably benign may obviate other patients having to undergo unnecessary hospitalization, anxiety, and expense.
Increased urinary excretion of free 20 alpha- and 20 beta-dihydrocortisol in a hypercortisolemic but hypocortisoluric patient with Cushing's disease.
Authors: Schöneshöfer M , Weber B , Nigam S
Published: January 2020

We identified non-metabolized, non-conjugated 20 alpha- and 20 beta-dihydrocortisol (20 alpha- and 20 beta-DHF) in urine from a patient with Cushing's disease, by use of three different liquid-chromatographic systems and by gas chromatography-mass spectrometry. We document that these 20-isomers of dihydrocortisol may strongly contribute to unspecific interferences with the immunological assessment of urinary free cortisol (F). The urinary excretion rates of 20 alpha- and 20 beta-DHF were quantified radioimmunologically with use of a cross-reacting cortisol antiserum after effective purification by liquid chromatography. The patient with Cushing's disease had mean peripheral cortisol concentrations of 1018 nmol/L. The urinary excretion rates (nmol/24 h) were 1455 for 20 alpha-DHF, 330 for 20 beta-DHF, and 18 for F. The corresponding reference values (median in nmol/24 h) were 174 for 20 alpha-DHF, 111 for 20 beta-DHF, and 68 for F (n = 22). We conclude that (a) specific estimation of urinary free F is not as highly sensitive for diagnosis of chronic hypercortisolemic states as is generally assumed; and (b) measurement of urinary free 20 alpha- and 20 beta-DHF or of the corresponding 20-DHF:F ratios may be more sensitive.