bluuebunny/crossref_metadata_2025 huggingface dataset:
Time--concentration studies by high-performance liquid chromatography of metabolites removed during hemodialysis.
Authors: Knudson E J , Lau Y C , Veening H , Dayton D A
Published: January 2020

Reversed-phase high-performance liquid chromatography was used to study the efficiency of hemodialysis. The method, previously used to study uremic hemodialysate, was also found useful for analyzing other uremic biofluids, such as serum and urine. Samples of blood (centrifuged to obtain cell-free serum) and hemodialysate were simultaneously collected from selected patients at regular intervals during the entire 6-hour hemodialysis treatment. These samples were filtered through membranes to remove particulates and proteins and were then analyzed by use of a 60-cm muBondapak-C18 column, an aqueous sodium acetate/methanol gradient, and detection at 254 nm. The identification of components in the eluate was based on retention times, ultraviolet absorption spectra, and mass spectra. From the amounts of several metabolites in the various physiological fluid pools during hemodialysis, we concluded that they mostly originate from tissue fluids. We also observed that the concentrations of most components in serum and hemodialysate fluctuated regularly with time.
Gas-chromatographic determination of nanogram amounts of enantiomers of nortilidine, a main metabolite of tilidine, in biological specimens.
Authors: Hengy H , Vollmer K O , Gladigau V
Published: January 2020

We report a specific and sensitive method for determination of the individual optical isomers of nortilidine, a main metabolite of tilidine, with the aid of a nitrogen-sensitive detector. With N-trifluoroacetyl-L-leucyl chloride as chiral reagent, the diastereomeric derivatives of the nortilidine enantiomers could be separated and quantified in the nanogram range. Under these conditions, the enantiomers of bisnortilidine, another main metabolite of tilidine, were also separated. Investigations in rats with the enantiomers of tilidine and nortilidine indicated that no racemization occurs during N-demethylation in the organism. After oral and intravenous administration of 50 mg of tilidine.HCI to a human volunteer, identical concentrations of nortilidine enantiomers were found in the plasma.
Cross reactivity of digitoxin and spironolactone in two radioimmunoassays for serum digoxin.
Authors: Müller H , Bräuer H , Resch B
Published: January 2020

We measured the cross reactivity of two medications--digitoxin and spironolactone--in two digoxin radioimmunoassay (liquid and solid-phase) kit procedures. Both tests showed similar average percentages of cross reactivity with digitoxin (7.2 and 8.9% for intravenous, and 11.9 and 10.9% for oral administration), but no cross reactivity with spironolactone or its metabolites after equal intravenous or oral doses.
Comparative determination of phenytoin by spectrophotometry, gas chromatography, liquid chromatography, enzyme immunoassay, and radioimmunoassay.
Authors: Castro A , Ibanez J , DiCesare J L , Adams R F , Malkus H
Published: January 2020

Sera from patients being treated with phenytoin were analyzed for the drug by spectrophotometry, gas chromatography, radioimmunoassay, enzyme immunoassay, and liquid chromatography. The essay values obtained were intercompared statistically. Enzyme immunoassay and liquid chromatography appear to be attractive alternatives to the more traditional methods of spectrophotometry and gas chromatography. Our radioimmunoassay data correlated poorly with results by the four other methods.
Micromethod for determination of creatinine in biological fluids by high-performance liquid chromatography.
Authors: Soldin S J , Hill J G
Published: January 2020

We describe a procedure for the rapid and specific measurement of creatinine, in which it is separated from other compounds in serum or urine by paired-ion chromatography and is quantified by measuring its absorbance at 200 nm. The procedure can be done on as little as 10 microliter of serum. Between-day precision studies for concentrations of 13 and 62 mg/liter yielded coefficients of variation of 6.9 and 2.2%, respectively. Analytical recovery of various amounts of creatinine added to plasma exceeded 95% in all cases. The proposed procedure was compared with the continuous-flow procedure by analyzing a series of serum and urine specimens by both methods. There was excellent agreement for urine specimens, but with serum the results by the present method were significantly (P less than 0.001) lower.
High-performance liquid-chromatographic assay for chloramphenicol in biological fluids.
Authors: Thies R L , Fischer L J
Published: January 2020

We describe a method for measuring chloramphenicol by high-performance liquid chromatography. The assay involves a single extraction of the biological sample with ether, evaporation of the extract, and chromatography of the residue, redissolved in methanol. A reversed-phase column with an eluting solvent of methanol/water (30/70 by vol) is used. Chloramphenicol is eluted from the column in about 4 min and is well separated from the internal standard (mephenesin), which is eluted at 5.5 min. Absorption of the effluent at 278 nm is monitored and measured. As little as 0.1 microgram of the antibiotic can be analyzed after its extraction from a 0.1-ml sample. The method is suitable for rapid and specific analysis for the drug in plasma, urine, cerebrospinal fluid, and other biological fluids.
Two-point determination of plasma ammonia with the centrifugal analyzer.
Authors: Bruce A W , Leiendecker C M , Freier E F
Published: January 2020

A simple, convenient, and rapid method for determining ammonia in plasma by the glutamate dehydrogenase reaction is described for the centrifugal analyzer. The measuring principle is fixed-time, with NADH as the coenzyme. ADP is added to stabilize glutamate dehydrogenase and prevent interference from endogenous plasma ADP. The reaction is linear to 400 mumol of ammonia per liter. The plasma sample volume is 100 microliter and the whole procedure takes only 25 min, including the 15-min preincubation. The normal range for venous plasma was 44 +/- 13.5 (SD) mumol of ammonia per liter.
Simple, rapid method for determination of propionic acid and other short-chain fatty acids in serum.
Authors: Hillman R E
Published: January 2020

A semimicro method for measuring propionic and other short-chain fatty acids in serum is presented. The procedure requires as little as 200 microliter of serum. Data are provided for premature infants, children, adults, and patients with propionicacidemia.
N-Ethylmaleimide prevents destruction of corticotropin (ACTH) in plasma.
Authors: Jubiz W , Nolan G
Published: January 2020

Addition of N-ethylmaleimide, an inhibitor of proteolytic enzymes, to samples for plasma corticotropin determinations prevents destruction of the hormone at room temperature for at least 72 h. A concentration of 125 mg per liter of blood is effective. N-Ethylmaleimide is not so effective in preventing corticotropin degradation in whole blood. Use of the inhibitor should make plasma corticotropin determinations more practical and reliable.
An interlaboratory study of measurement of aspartate aminotransferase activity with use of purified enzyme materials.
Authors: Burtis C A , Sampson E J , Bayse D D , McKneally S S , Whitner V S
Published: January 2020

The Center for Disease Control (CDC), the New York State Department of Health (NYSDH), the College of American Pathologists, and 23 manufacturers of diagnostic products participated in an interlaboratory study of aspartate aminotransferase (EC 2.6.1.1) methodologies. Six different lyophilized materials were prepared and characterized and then distributed to 293 laboratories for aspartate aminotransferase measurements. The specimens included one human serum; four catalytic concentrations of the cytoplasmic isoenzyme, two purified from human erythrocytes, and two from porcine heart; and one matrix bovine serum albumin (30 g/liter) blank. The purified isoenzymes were prepared in the matrix. We present data on Michaelis parameters (Km and Vmax), Arrhenius plots, activation with pyridoxal 5-phosphate, vial-to-vial variability, and stability on reconstitution. The 281 responses showed that most of the laboratories used NADH-detection methods (91.1%), monitored at 340 nm (79.4%), and reported results in U/liter (89.4%). The percentage of laboratories reporting use of reaction temperatures of 30 and 37 degrees C was evenly divided, i.e., 42.7 and 42%, respectively. Analytical values reported by participating laboratories were categorized by reporting temperature, instrument, and method. Results were most consistent for a selected group of laboratories that supplemented optimized reaction solutions with pyridoxal 5-phosphate.
Factors affecting measurement of total alkaline phosphatase activity in human serum, especially wavelength accuracy.
Authors: Lott J A , Turner K , Scott J
Published: January 2020

Serum alkaline phosphatase estimations by the Selected Method [Clin. Chem. 21, 1988 (1975)] are very sensitive to small errors in the wavelength setting of the spectrophotometer. With a setting error as small as 3 nm, results can be too low by as much as 23%. The product of the reaction, 4-nitrophenol, can be prepared in very pure form and can be used to check both the wavelength and absorbance accuracy of a spectrophotometer. The molar absorptivity for 4-nitrophenol obtained in the instrument being used should be used in calculating alkaline phosphatase activities.
Biochemical properties of tartrate-resistant acid phosphatase in serum of adults and children.
Authors: Lam W K , Eastlund D T , Li C Y , Yam L T
Published: January 2020

Spectrophotometry of total acid phosphatase activity in children's sera showed an average value of 22.4 +/- 2.9 and 7.4 +/- 0.8 U/liter, for the hydrolysis of p-nitrophenyl phosphate and alpha-naphthyl phosphate, respectively. Analyses of "band 5b", after electrophoresis on acrylamide gel, gave even higher values. The values for children's sera were much higher than those for sera from adults. The multiplicity of acid phosphatases in sera of children and adults was studied by electrophoresis on acrylamide gel and by chromatography on CM-Sepharose. Both methods showed the major acid phosphatase in children's sera to be an acid pyrophosphatase, band 5b. Its catalytic properties are indistinguishable from the enzyme previously isolated from the spleen of leukemic reticuloendotheliosis.
Use of a programmable desk-top calculator for the statistical quality control of radioimmunoassays.
Authors: Cernosek S F , Gutierrez-Cernosek R M
Published: January 2020

We have developed an interactive statistical quality-control system for the small- to medium-sized radioimmunoassay laboratory, which can be used in a programmable desk-top calculator instead of the medium- or large-scale computer systems usually required. The design of this quality-control system is modeled after the suggestions of Rodbard and has three components. The first component evaluates the relationship between the measured response variable of the radioimmunoassay and the precision (or variance) of these measurements. This derived relationship is then used in the second component of the system as the basis for the weighting function used to calculate an interative, weighted, least squares regression of the logit-log transformation of the dose-response curve. The third component uses the quality-control parameters statistically calculated from the linearized dose-response curve to monitor whether the assay is "in-control". The calculator tabulates the means and confidence limits for the various parameters and can plot the statistical quality-control charts. The major benefit of this statistical quality-control system is that it allows the real-time computation and plotting of quality-control data with a programmable desk-top calculator.
Hexosaminidase A in amniotic fluid of Tay-Sachs fetuses.
Authors: Geiger B , Navon R , Arnon R
Published: January 2020

Hexosaminidase A is present in relatively low concentrations in cell-free amniotic fluids from pregnancies with Tay-Sachs fetuses. This isoenzyme was determined by an immunological procedure, radial immunodiffusion, by which hexosaminidase A can be directly and specifically detected, even in the presence of excess amounts of hexosaminidase B. No hexosaminidase A could be detected by the same procedure in Tay-Sachs fetal tissues, implying that this isoenzyme in the amniotic fluid originates from the mother.
Simultaneous determination of phosphatidylglycerol and the lecithin/sphingomyelin ratio in amniotic fluid.
Authors: Gotelli G R , Stanfill R E , Kabra P M , Farina F A , Marton L J
Published: January 2020

We describe a single-dimension thin-layer chromatographic method by which one can simultaneously determine the lecithin/sphingomyelin ratio and the proportion of phosphatidylglycerol in amniotic fluid. The phospholipids are conveniently detected by an improved molybdenum-blue spray reagent, which immediately produces blue spots on a white background. The stained phospholipids are stable for at least 90 min after spraying, and densitometry results in symmetrical peaks that are easily quantitated.
Improved methods for isolating cortisol metabolites from neonatal urine.
Authors: Derks H J , Drayer N M
Published: January 2020

Urine was collected from newborns, children, and adults who had received a tracer dose of [3H] cortisol. The free and different types of conjugated cortisol metabolites were separated by ion-exchange chromatography. A modified Amberlite XAD-2 procedure was used, which enabled quantitative extraction of the extremely polar cortisol metabolites from urine from newborns. Large differences between the ion-exchange chromatographic patterns for neonates and adults were observed. Urine from neonates was shown to contain quantitatively important amounts of an as-yet-unidentified conjugate that was absent from urine from adults. The effects of three different hydrolytic methods on the neonatal steroid conjugates were studied and it was found that the unknown conjugate in urine from the newborn could be hydrolyzed by solvolysis only.
Biochemical characterization of an aryl acetic ester hydrolase isolated from human monocytes.
Authors: Lam W K , Taft E , Yam L T
Published: January 2020

A carboxylic-ester hydrolase was isolated from the leukocytes of a patient with myelomonocytic leukemia. Its relative molecular mass as estimated by sucrose density-gradient sedimentation is about 70 000. The purified enzyme is specific for acetyl esters of aromatic alcohols. It is inhibited by fluoride, but insensitive to eserine or p-chloromercuriphenylsulfonate. Hydrolysis of 1-naphthyl acetate was optimal above pH 6.0; of o-nitrophenyl acetate, above 8.0. The common catalytic site for the two types of substrates on the enzyme was confirmed by competitive inhibition data.
Effect of temperature on plasma renin samples.
Authors: Fyhrquist F , Puutula L
Published: January 2020

Plasma renin activity was measured in parallel in Na2EDTA-contained plasma samples after storage at -20, 4, and 24 degrees C, and in the lyophilized state. In peripheral venous plasma from 22 hypertensive patients, the activity (range, 0.08-46.7 microgram/liter per hour) remained stable during three days of storage at 4 degrees C, but decreased to a variable extent when plasma was kept at 24 degrees C: in one day by 9.2%, two days by 25.6%, and three days by 74.0%. Values were the same for samples handled at room temperature and chilled to 4 degrees C within 3 h and parallel samples immediately cooled in an icebath and kept at 4 degrees C. Freezing (-20 degrees C) and thawing of plasma was associated with a 22% mean increase in activity (range, 0-83%). Lyophilization resulted in a smaller increase of plasma renin activity (mean 12%, range 0-46%). Blood for renin analysis need not be cooled immediately, but must be cooled to 4 degrees C within 2-3 h. It then is stabe for at least three days. Freezing or lyophilization appears to be associated with some cold activation of "prorenin."
A melting-point-of gallium apparatus for thermometer calibration.
Authors: Sostman H E , Manley K A
Published: January 2020

We have investigated the equilibrium melting point of gallium as a temperature fixed-point at which to calibrate small thermistor thermometers, such as those used to measure temperature in enzyme reaction analysis and other temperature-dependent biological assays. We have determined that the melting temperature of "6N" (99.999% pure) gallium is 29.770 +/- 0.002 degrees C, and that the constant-temperature plateau can be prolonged for several hours. We have designed a simple automated apparatus that exploits this phenomenon and that permits routine calibration verification of thermistor temperature probes throughout the laboratory day. We describe the physics of the gallium melt, and the design and use of the apparatus.
Rapid assessment of isoenzymes by high-performance liquid chromatography.
Authors: Schlabach T D , Alpert A J , Regnier F E
Published: January 2020

We describe the rapid profiling of isoenzymes by use of microparticulate anion-exchange chromatography supports and a continuous, post-separation enzyme detector in a high-performance liquid chromatograph. Chromatographic analysis and enzyme detection are fully automated and provide excellent reproducibility. Factors affecting the isoenzyme profile and detector response characteristics are assessed. Lactate dehydrogenase and creatine kinase isoenzymes in tissue extracts, control materials used as electrophoretic standards, and serum were profiled by this method to establish the resolution and reliability of the method. We show the clinical use of this method in detecting changes in these isoenzymes in serum associated with acute myocardial infarction.
Automated system for fractionation of blood samples.
Authors: Lee N E , Genung R K , Johnson W F , Mrochek J E , Scott C D
Published: January 2020

We describe a prototype system for preparing multiple fractions of blood components (plasma, washed erythrocytes, and hemolysates) by use of automated techniques. The procedure is based on centrifugal separation and sample transfer by induced pressure differentials in a blood-processing vessel (rotor) that has been designed to process 24 samples simultaneously. Erythrocytes are sedimented against the outer walls of individual sample chambers, and plasma is siphoned, by imposition of either a slight positive or negative pressure, into individual reservoirs in a collection ring. Cells are washed in situ; samples of washed cells, either packed or in saline solution, can be recovered. Cellular hemolysates are automatically prepared and transferred to individual, commercially available collection vials, ready for immediate analysis or for storage in liquid nitrogen. The system has potential application in any biomedical area in which many samples are to be expeditiously analyzed and in which one or more of the blood fractions will be used. A separate unit has been designed and developed for the semiautomated cleaning of the rotor.
Improved approach to sequential addition immunoassay.
Authors: Lasky F D , Al Razi J , Karmen A
Published: January 2020

In the usual sequential addition enzyme immunoassays for drugs, the activity of the drug-labeled enzyme decreases continuously with time as more of it is bound to antibody. Sensitivity also decreases; the activity immediately after mixing is the most sensitive indicator of drug concentration. The reaction of enzyme-drug with antibody can be stopped by saturating the antibody with a larger quantity of unlabeled drug, which reacts with the antibody faster than does the enzyme-labeled drug. When drug is added soon after the reaction starts, the enzyme activity is stabilized and the sensitivity to small quantities of antigen is increased. This approach, with modification, should be applicable to sequential immunoassays in which other kinds of labels are used. The enzyme activity can be measured for a longer time, with the predictable increase in precision, as well as the ability to detect smaller quantities, to use less reagent, and to use end-point rather than kinetic assays.
Comparison of three radioligands, selenium-75, lodine-125, and tritium, in the radioimmunoassay of methotrexate.
Authors: Paxton J W , Rowell F J , Cree G M
Published: January 2020

Radioimmunoassays for methotrexate are described, involving use of a rabbit antiserum to a conjugate of the drug and bovine serum albumin and the drug labeled with tritium, selenium-75, or iodine-125. Of the two gamma emitters, the 75Se-labeled drug was prepared by the Radiochemical Centre, Amersham, England and the 125I-labeled drug in the laboratory, by the Chloramine T iodination technique. The stability of labels with both methods allows use of the faster, cheaper, and simpler gamma-counting techniques, with results available after 3 h. All three methods have acceptable sensitivity, accuracy, precision, and reproducibility, and are specific for methotrexate, with no significant interference from naturally occurring folates or leucovorin. The assays in which the gamma emitters are used have significant practical advantages over the beta emitter and are much better suited to automation and clinical application. The main advantage of 75Se=labeled methotrexate is its longer half-life, 121 days, as compared with 60 days for 125I.
Creatine kinase in serum: 5. Effect of thiols on isoenzyme activity during storage at various temperatures.
Authors: Szasz G , Gerhardt W , Gruber W
Published: January 2020

We studied changes in the activity of human creatine kinase isoenzymes (native MM in serum, MM, MB, and BB preparations in serum matrix) on storage in the presence of 0, 10, 20, and 50 mmol of N-acetyl cysteine, 2-mercaptoethanol, and 1-thioglycerol per liter of serum at 37, 30, 25, 4, and -20 degrees C. We also assessed the stability of the thiols under the same conditions. We generally confirmed increasing stability in the sequence: BB, MB, and MM isoenzyme. Above 30 degrees C irreversible inactivation is very rapid, even in the presence of thiols. At lower temperatures endogenous MM is sufficiently stable; thus, the use of protective thiols can be restricted to sera expected to contain isoenzymes MB or BB. Our studies lead us to prefer use of 50 mmol of N-acetyl cysteine per liter of serum. The other thiols cause turbidity to develop earlier and their decomposittion products diminish the activity more. The initial activity of the MB and BB preparations increased by as much as 2.3- and 1.8-fold on storage with thiols. This effect was not observed with either endogenous MB and MM or with the MM prepartion.
Emergency procedure for digoxin radioassay.
Authors: Chen I W , Sperling M , Volle C , Maxon H R
Published: January 2020

A rapid but precise radioassay for digoxin has been developed by optimizing the conditions for antigen-antibody interaction and for separation of bound and free fractions. This new procedure involves incubation of radioactively labeled antigen, antibody, and standard or sample at 3 degrees C for 10 min. Charcoal is then added, the mixture centrifuged for 5 min, and the radioactivity of the supernate counted. Results are available in less than 1 h after receipt of the specimens, making the procedure suitable for emergency determinations. Results correlate well with those by our routine procedure (Becton Dickinson) (r = 0.9739, y = 0.0356 + 0.9915x, n = 49). Analytical recovery of added pure digoxin exceeds 94%, both within and between assay CV's are less than 8%.
Improved thin-layer chromatographic method in the diagnosis of mannosidosis.
Authors: Friedman R B , Williams M A , Moser H W , Kolodny E H
Published: January 2020

An improved thin-layer chromatographic method is described for the facile separation of neutral oligosaccharides excreted in the urine of patients with mannosidosis. The urine sample is treated with mixed-bed ion-exchange resin to remove charged species. The eluate is then chromatographed on silica gel thin-layer plates with n-propanol water as the developer. Eleven unique orcinol-positive components can thus be resolved. The advantages of this method over previously described techniques are the ease and rapidity of assay, better resolution of components, and clarity of resolution. It should be applicable to other disease states in which distinctive neutral carbohydrate products are produced.
Double-antibody enzyme immunoassay for nortriptyline.
Authors: Al-Bassam M N , O'Sullivan M J , Gnemmi E , Bridges J W , Marks V
Published: January 2020

beta-D-Galactosidase (EC 3.2.1.23) from Escherichia coli was conjugated to desmethylnortriptyline by means of a bifunctional cross-linking reagent, dimethyl adipimidate, and used in a double-antibody immunoassay for nortriptyline. Eighty percent of the enzyme activity was retained after conjugation; 75% of the enzyme was conjugated to desmethylnortriptyline. In the final immunoassay the enzyme activity of the bound fraction was determined with o-nitrophenyl-beta-D-galactopyranoside as substrate. The sensitivity, precision, and simplicity of the enzyme immunoassay compared favorable with that of a published radioimmunoassay method. Results for nortriptyline in plasma samples correlated well with those determined by either radioimmunoassay or gas-chromatography.
An impurity in the buffer 2-amino-2-methyl-1-propanol, which correlates with depression of measured alkaline phosphatase activity.
Authors: Williamson J A , Thompson J C
Published: January 2020

Recent findings indicate that the buffer 2-amino-2-methyl-1-propanol, widely used in clinical measurement of alkaline phosphatase activity, contains an impurity that inhibits the activity of the enzyme. Analysis of several lots of 2-amino-2-methyl-1-propanol has demonstrated the presence of a material, the concentration of which correlates well with alkaline phosphatase activity. Mass spectral analysis of this material indicates that it is a substituted ethylenediamine compound. Zinc chelation is discussed as a possible mode of its inhibition. Further work is in progress to separate and characterize this and other compounds in the buffer and to determine their modes and degrees of alkaline phosphatase inhibition.
Triiodothyronine uptake test in which antibody-coated tubes are used compared to two other tests in which precipitation separations are used.
Authors: Szpunar W E , Block M
Published: January 2020

A triiodothyronine uptake test in which antibody-coated tubes are used (Clinical Assays) was compared to two other such tests in which silicate tablets (Nuclear-Medical Laboratories, Inc.) or macroaggregated albumin (Diagnostic Corporation of America) are used to separate the bound from the free fraction. The Clinical Assays test showed good linear correlation with the values obtained by the other two tests on 67 samples. The interassay coefficient of variation was 4.8%. The correlation between the values obtained and the clinical evaluation on 60 patients also was essentially the same as for the other two tests, 80%.
Quality control of measurements of pH, carbon dioxide tension, and total carbon dioxide in plasma.
Authors: Savory D J , Pryce J D
Published: January 2020

We have measured total carbon dioxide in plasma with a new carbon dioxide analyzer, and compared the results with total carbon dioxide data derived from measurements of carbon dioxide tension and pH. The results agree sufficiently well to demonstrate that the new instrument provides a simple, efficient procedure for monitoring the precision and accuracy of pH, carbon dioxide tension, or total carbon dioxide in plasma.
Kinetic measurement of alpha-amylase with a centrifugal analyzer.
Authors: Iosefsohn M , Hicks J M
Published: January 2020

We compared results of an enzymic assay for alpha-amylase (EC 3.2 1.1), adapted to a centrifugal analyzer (GEMSAEC), with results by the manual dyed-starch (Phadebas) amylase assay. We assessed linearity and precision, and the stability of the reagent. The kinetic procedure is rapid, precise, requires only 25 microliter of serum, and thus is evidently suited for both pediatric and emergency use.
Enzymic assay for lecithin in amniotic fluid.
Authors: Anaokar S , Garry P J , Standefer J C
Published: January 2020

We describe an enzymic method for determining lecithin in amniotic fluid. Phospholipase D from savoy cabbage is used to liberate choline from lecithin, and the liberated choline is oxidized to betaine and hydrogen peroxide by choline oxidase from Arthrobacter globiformis. The hydrogen peroxide forms a colored complex with phenol and 4-aminoantipyrene in the presence of horseradish peroxidase, and this color is measured spectrophotometrically. The method is relatively easy, precise, and accurate, requires less time and sample than other methods, and offers a reliable alternative to the lecithin/sphingomyelin ratio techniques for assessing fetal lung maturity.
Radioimmunoassay for pantothenic acid in blood and other tissues.
Authors: Wyse B W , Wittwer C , Hansen R G
Published: January 2020

We describe a radioimmunoassay for pantothenic acid in biological tissues. D-Pantothenic acid was conjugated with bovine serum albumin by use of a bromoacetyl derivative of pantothenic acid, and antibody to this antigen was raised by injecting it into the foot pads of rabbits. For the radioimmunoassay, a 100-fold dilution of the resulting antiserum was incubated with radiolabeled pantothentic acid. The antibodies were precipitated and dissolved, and the radioactivity of the solution was measured in a liquid scintillation counter. Between 5 and 125 ng of pantothenic acid can be detected in 75 muL of tissue extract. Validation included recovery and precision studies, parallelism with tissue extracts, and competitive binding studies. Results of the radioimmunoassay and those of microbiological assay with use of Lactobacillus plantarum correlated well (r = 0.80).
Cell-surface receptors in health and disease.
Authors: Blecher M
Published: January 2020

Assessment of interaction of hormones and neurotransmitters with their cell-surface receptors can lead to an understanding of the molecular mechanisms that underlie diseases in man involving resistance and supersensitivity to these humoral agents and to pharmacological agents. They can also lead to the development of simple diagnostic procedures for such disorders, as well as the development of radioreceptor assays for humoral agents and drugs in blood and tissues, assays which combine sensitivity comparable to those involving radiommunoassay with a greater biological accuracy.
Absorbance measurement in cuvettes lying longitudinal to the light beam.
Authors: Eisenwiener H G , Keller M
Published: January 2020

Measurement in cuvettes with their longitudinal dimension parallel to the light beam, while under the influence of a centrifugal force, has many advantages that are not immediately apparent. This survey summarizes the advantages in comparison to cuvettes standing with their long axis perpendicular to the light beam: in the latter the pathlength is fixed by the geometry, but if the cuvette is lying longitudinal to the light beam the pathlength is given by the filling volume. Because of the dependence of the pathlength on the filling (reaction) volume when cuvettes are lying longitudinal to the light beam, the calculation formulas show that the calculation factors, both for enzyme and substrate determination, become independent of the reagent volume form. This is demonstrated by simple equations and confirmed in practice by use of the (Cobas) Bio centrifugal analyzer in assays for glucose and aspartate aminotransferase.
Comparison of three iodination methods for human somatotropin.
Authors: Apinyacharti P , Baxter R C
Published: January 2020

Human somatotropin (growth hormone) iodinated by use of lactoperoxidase or Chloramine T added stoichiometrically has been compared with hormone iodinated by conventional Chloramine T method. The three preparations were indistinguishable, both in their stability to storage and in their suitability for use in radioimmunoassay. Degradation of tracer, as measured by decreasing precipitability with trichloroacetic acid, was found to be an unsatisfactory measure of immunoreactivity, because aggregates of high relative molecular mass formed during storage at--15 or--80 degrees C are less immunoreactive.
Improved method of purifying some radiolabeled glycopeptide hormones.
Authors: Patritti-Laborde N , Yoshimoto Y , Wolfsen A , Odell W D
Published: January 2020

We describe a simplified method for purifying radiolabeled glycopeptide hormones (thyrotropin, lutropin, follitropin, and human choriogonadotropin), which results in preparations of over 95% immunoreactivity. This method is based on competitive elution from columns of the plant lectin, concanavalin A, and is applicable to glycopeptide hormones derived from several species.
Double light-chain disease: a case report.
Authors: Dalal F R , Winsten S
Published: January 2020

A patient with massive proteinuria was discovered to have double light-chain disease. Immunological studies demonstrated monoclonal light chains of both the lambda and kappa type in urine. The light chains were separate and distinct and were not found to be a part of any of the whole molecule immunoglobulins such as IgG, IgM, IgA, IgD, or IgE. Uniqueness of the proteins was confirmed by column chromatography. Clinical studies showed that the patient had multiple myeloma.
Stability of dried blood spots on paper, as used in screening neonates for hypothyroidism.
Authors: Davis G , Poholek R
Published: January 2020

Thyroxine values for dried blood spots on paper may be low if the paper has been long exposed to high ambient temperature and (or) humidity and (or) to sunlight. Low values are associated with poor extractability of the red color from the spots. We recommend appropriate precautions for such samples.
Evaluation of a commercial enzyme immunoassay for insulin in human serum, and its clinical application.
Authors: Yoshioka M , Taniguchi H , Kawaguchi A , Kobayashi T , Murakami K , Seki M , Tsutou A , Tamagawa M , Minoda H , Baba S
Published: January 2020

We applied a "sandwich" method, with use of beads coated with anti-insulin serum and of peroxidase-labeled anti-insulin serum, to an enzyme immunoassay of insulin in human serum. 5-Aminosalicylic acid was used as the substrate for the enzymic reaction. As little as 5 milli-int. units of insulin per liter of serum insulin was detectable. Reproducibility was satisfactory, but extraordinarily high concentrations of proinsulin and of hydrogen donors such as reduced glutathione affect results of the assay. Values determined by our enzyme immunoassay and by double-antibody radioimmunoassay correlated highly (r = 0.938, p less than 0.001, n = 216). We recommend this method for use in the clinical laboratory.
On-line continuous potentiometric measurement of potassium concentration in whole blood during open-heart surgery.
Authors: Osswald H F , Asper R , Dimai W , Simon W
Published: January 2020

We describe a flow-through system with an ion-selective electrode for measurement of blood potassium ion concentration, continuously and on-line off the extracorporeal blood circulation in an operating theater during human open-heart surgery. Comparison measurements were made with the SMA flame photometer (blood plasma) and an Orion SS 30 sodium/potassium analyzer (whole blood). The potassium concentration values obtained with the flow-through system agree well with the ones determined with the flame photometer. The time delay of the measurement with the flow-through system was relatively long (2 min) but delays of only 10--20 s seem feasible. Short time delays can deepen insight and simplify rational treatment under surgery conditions.
Spironolactone-associated digoxin radioimmunoassay interference.
Authors: Silber B , Sheiner L B , Powers J L , Winter M E , Sadée W
Published: January 2020

Apparent digoxin was measured in the serum of 21 patients receiving spironolactone and in 21 controls, by use of a sequential-saturation 3H-radioimmunoassay (RIA) and an equilibrium 125I-RIA. No patient had been given digoxin for at least four weeks. "Digoxin" values in the former group were significantly (p less than 0.05) higher than in the control group, and often were in or near the "therapeutic" range by the equilibrium 125I-RIA, but not by the sequential-saturation 3H-RIA. Canrenone (a major active metabolite of spironolactone) in the serum of the former group was measured by a newly developed liquid-chromatographic technique and correlated (r = 0.73) with "digoxin" concentrations by the 125I-RIA. However, external addition of canrenone to control serum in comparable concentrations did not cause appreciable "digoxin" values by the 125I-RIA. These findings suggest that other metabolites of spironolactone are responsible for the assay interference, the degree of which appears to depend on antibody specificity. Therefore, assay specificity should be established in clinical laboratories by using digoxin-free serum from patients ingesting spironolactone, and not by using spironolactone- or canrenone-fortified digoxin-free serum.
Blood cyanide and thiocyanate concentrations after administration of sodium nitroprusside as hypotensive agent in neurosurgery.
Authors: Bogusz M , Moroz J , Karski J , Gierz J , Regieli A , Witkowska R , Gołabek
Published: January 2020

In a group of 50 neurosurgical patients receiving sodium nitroprusside as a hypotensive agent, in doses of 50--2131 microgram/kg body weight, whole blood cyanide was estimated before infusion of drug, during infusion, immediately after infusion, and 1 and 3 h later. Cyanide values increased significantly, reaching the maximum in a sample taken immediately after infusion (mean value, 333; highest value, 1800 microgram/liter). Values correlated closely with both dose and rate of infusion. Blood thiocyanate, estimated before, immediately after, and 3 h after the infusion, showed no significant changes in thiocyanate concentration. In any case, no signs or symptoms of cyanide or thiocyanate poisoning were observed. We conclude that sodium nitroprusside, in the proper dose and given at the proper rate, does not precipitate cyanide poisoning.
Comparison of liquid- and gas-liquid chromatographic assays of 5-fluorouracil in plasma.
Authors: Christophidis N , Mihaly G , Vajda F , Louis W
Published: January 2020

A liquid-chromatographic assay of 5-fluorouracil in plasma is described. Advantages of this procedure over gas chromatography are the simpler extraction procedure, elimination of the need for a derivitization step with silylating agents, and a 20-fold greater sensitivity. The minimum detectable concentration of 5-fluorouracil in plasma is 25 microgram/L. The enhanced sensitivity enabled measurement of the concentrations of 5-fluorouracil found in plasms of patients receiving continuous intravenous infusions of the drug; such concentrations are generally unmeasurable by gas-chromatographic methods. We compared liquid-chromatographic and gas-chromatographic measurements on 36 plasma samples obtained from patients after rapid intravenous injection of 5-fluorouracil. The resulting correlation coefficient was 0.97, with a regression slope of 0.94. The liquid-chromatographic method is free of interference from other cytotoxic agents, anti-emetics, and folate derivatives that are frequently combined with 5-fluorouracil therapy.
Arylesterase in serum: elaboration and clinical application of a fixed-incubation method.
Authors: Lorentz K , Flatter B , Augustin E
Published: January 2020

A sensitive, specific, and simple method for determining serum or urine arylesterase (EC 3.1.1.2) is described. The enzyme acts on phenyl acetate to release phenol, which produces a stable indophenol dye with 4-aminoantipyrine and potassium ferricyanide. Arylesterase, a thiol enzyme, is reactivated by 2-mercaptoethanol and by cysteine, but not by reduced glutathione. Calcium is indispensable to stabilize and to activate (Km = 0.85 mmol/L) the enzyme; complete protection is achieved at CaCl2 20 mmol/L. Magnesium acts as a weak (Ki = 116 mmol/L), lanthanum as a potent (Ki = 5 mumol/L) competitive inhibitor. The activity is measured in diluted sera at phenyl acetate 4.0 mmol/L (Km = 1.12 mmol/L), pH 7.8 and 25 degrees C. The normal range extends from 53 to 186 kU/L, and four isoenzymes are present in sera from healthy adults. Arylesterase decreases in hepatic disorders, especially in cirrhosis and carcinoma of the liver, with reduction of the penultimate fraction in polyacryalmide gel electrophoresis.
The use of immobilized enzyme reactors in continuous-flow analyzers for the determination of glucose, urea, and uric acid.
Authors: Chirillo R , Caenaro G , Pavan B , Pin A
Published: January 2020

We describe the use of immobilized enzymes in assay methods for the determination of glucose with glucose oxidase, uric acid with uricase, and urea with urease in serum samples. The enzyme reactor tubes were adapted to continuous-flow analyzers (Technicon AA II, SMA 12/60, and SMAC) used in routine laboratory determinations, and results with their use were compared to those from assays involving soluble enzymes. We substituted the reactors for the free enzyme reagents in the respective channels of the SMA 12/60 and SMAC, without modifying the parameters of the remaining channels. We compared assay sensitivity, precision, and carryover for immobilized and conventional liquid enzymes. Immobilized enzyme reactors provide accurate, reliable, convenient, and economical alternatives to the use of free enzyme reagents in these systems.
Identification of alpha1-lipoproteins in crossed immunoelectrophoresis.
Authors: Cline L J , Crowle A J
Published: January 2020

Evans Blue dye binds selectively, but with different avidities, to five major antigens in human serum. The anodic mobility of the antigen-dye complexes is greater than that of the antigens alone in crossed immunoelectrophoresis, which is of practical value for identification. We used this characteristic to show that in some human sera there is a population of alpha1-lipoprotein molecules that migrates electrophoretically in the beta-lipoprotein region, where in conventional zone electrophoresis it could be mistaken for beta-lipoprotein. We also demonstrate that horses, unlike rabbits, rarely make precipitins to human serum alpha1-lipoprotein. Equine antiserum to human serum therefore generally is useless for detecting this important serum antigen in immunoelectrophoresis.
Influence of posture on free calcium and related variables.
Authors: Renoe B W , McDonald J M , Ladenson J H
Published: January 2020

We measured free calcium and related variables before and after the subject changed from the upright to the supine posture, doing 15 separate such experiments on 11 healthy men. After such a change, free calcium (1.7 +/- 0.4%), total calcium (4.6 +/- 0.7%), total protein (11.5 +/- 1.4%), albumin (12.2 +/- 2.0%), total magnesium (3.8 +/- 0.9%), and the activity of hydrogen ion (2.9 +/- 1.0%) decreased significantly (values are means +/- SEM), but promptly reverted when three subjects assumed the alternative posture. Changes in lactate values were not rapidly reversible; sodium and potassium showed no significant change. The mechanism of the changes in free calcium is unclear, but they correlated only with the changes in total calcium and were notably less than the changes in total calcium, indicating that posture will have less effect on the interpretation of free calcium values than on values for total calcium.
Measurement of 4-hydroxyphenylacetic aciduria as a screening test for small-bowel disease.
Authors: Chalmers R A , Valman H B , Liberman M M
Published: January 2020

We evaluted measurement of urinary 4-hydroxyphenyl acetic acid as a potential screening method for small-bowel disease and bacterial overgrowth syndromes in 360 unselected acutely ill infants and children. Control data were obtained on 120 healthy children, ages 1.5 to 15 years, from a general medical practice, 48 healthy infants, ages one to five years, from local day nurseries, and 150 healthy babies, ages less than one to eight days. Comparative data were from 300 acutely ill hospitalized babies and children, ranging in age from less than one day to 15 years and without clinical evidence for small-bowel disease and bacterial overgrowth syndrome. No false-negative results and only 2% false-positive results were observed. Among the 10 patients whose urinary excretion of the analyte was considered to be abnormal were patients with Giardia lamblia infestation, ileal resection with blind loop, and other diseases of the small intestine associated with bacterial overgrowth. We conclude that measurement of 4-hydroxyphenylacetic acid excretion is useful in screening for such diseases.
Three different radioiodination methods for human spleen ferritin compared.
Authors: Bolton A E , Lee-Own V , McLean R K , Challand G S
Published: January 2020

We compared three different methods for radioiodination of human spleen ferritin. Tracers prepared by direct oxidative iodination with use of Chloramine T or 1,3,4,6-tetrachloro-3 alpha, 6 alpha-diphenylglycoluril (Iodogen) were structurally altered by the labeling procedure, as was made apparent by gel filtration and electrophoresis on polyacrylamide gel. Tracers prepared by conjugation to radioiodinated N-succinimidyl-6-(4-hydroxyphenyl)propionate retained their structural integrity, as assessed by physicochemical methods. Such tracers bound more than 90% in antibody excess, yielded self-displacement curves parallel to unlabeled ferritin standards, and retained their immunoreactivity for nine weeks. By contrast, immunological activity and stability of tracers prepared by the oxidative methods were less satisfactory. Tracers prepared by using lodogen were unsuitable for use in the ferritin radioimmunoassay because of shallow standard-inhibition curves and poor binding in the absence of added standard. Thus, we found the conjugation procedure to be the most suitable of the three methods for preparation of spleen-ferritin tracers.
Fluorometric measurement of theophylline.
Authors: Meola J M , Brown H H , Swift T
Published: January 2020

We have developed a simple, sensitive procedure in which theophylline in a solution of cerium(IV) acts as an oxidizable compound to produce fluorescent cerium(III) when combined with a microsolvent for extraction at pH 7.9. This method provides excellent sensitivity and specificity because other xanthines and phenobarbital, secobarbital, amobarbital, and phenytoin do not interfere. Day-to-day reproducibility (coefficient of variation, 6%) is attained for theophylline concentrations of 10 and 20 mg/L. Results correlate well with liquid chromatography and enzyme immunoassay procedures. Total analysis time for a single sample is 10 min.
Abrnomal lipoprotein patterns in human serum as determined by agarose gel electrophoresis.
Authors: Papadopoulos N M
Published: January 2020

Two groups of abnormal electrophoretic patterns of serum lipoproteins are reported here. One demonstrates a deficiency or absence of lipoprotein fractions, which is characteristic of patients with abeta-lipoproteinemia, hypo-beta-lipoproteinemia, or Tangier disease. The other shows the presence of extra lipoprotein fractions, as found in cholestasis and multiple myeloma. These patterns, together with those of hyperlipoproteinemia phenotypes previously reported (Clin. Chem. 24:227, 1978), form a reference record and a basis for the detection and evaluation of lipoprotein abnormalities in normal and dyslipoproteinemic subjects, as determined by a sensitive, accurate, rapid, and inexpensive electrophoretic technique.