bluuebunny/crossref_metadata_2025 huggingface dataset:
Plasma L-dopa in the diagnosis of malignant melanoma.
Authors: Faraj B A , Camp V M , Murray D R , Kutner M , Hearn J , Nixon D
Published: January 2020

We determined the concentration of L-dopa in the plasma of 98 patients with biopsy-proven melanoma, a dermatological neoplasm that is characterized biochemically by abnormal tyrosine metabolism. For 21 patients previously diagnosed as having melanoma but who were clinically free of disease (stage I), the mean concentration of L-dopa in plasma, 1.01 (SD 0.12) micrograms/L, was not significantly different from that of 32 normal controls, 1.23 (SD 0.16) micrograms/L. However, L-dopa was increased significantly (p less than 0.001) in the plasma of all of 65 patients with active disease (stage II), 2.08 (SD 0.46) micrograms/L, and was highest in 12 patients with stage III malignant melanoma, 8.40 (SD 3.50) micrograms/L. The development of metastases in four patients with stage II melanoma was accompanied by an increase in the concentration of plasma L-dopa. These studies suggest that measurement of plasma L-dopa may be useful in the diagnosis of melanoma.
Components of variance analysis of data produced in a national quality-control survey of radioimmunoassays of thyroxin, triiodothyronine, thyrotropin, prolactin, and progesterone.
Authors: Pilo A , Zucchelli G C , Chiesa M R , Bolelli G F , Albertini A
Published: January 2020

Data collected in a collaborative survey for radioimmunoassays have been studied by using analysis of variance to estimate the within-kit (CVw.kit) and the between-kit (CVb.kit) components of the total variability (CVT). This analysis has been applied to the results for triiodothyronine, thyroxin, thyrotropin, prolactin, and progesterone produced by 80-150 laboratories that assayed blind, replicate samples. Total variability was lowest in the thyroxin assay (CVT = 10.9%), associated with a very close between-kit agreement (CVb.kit = 4.0%); in the triiodothyronine assay, on the other hand, the large between-kit component (CVb.kit = 10.1%) increased the total variability to 16.1%. In the prolactin assay the CVT of 19.3% included 17.5% CVw.kit and 8.1% CVb.kit. Assays for thyrotropin and progesterone involve analyses of two pools at different hormone concentrations. The CVb.kit component was very high in the low-concentration pool, both for thyrotropin (25.1%) and progesterone (45.2%); in the higher-concentration pool it decreased to 8.3% for thyrotropin but remained high (21.6%) for progesterone. Applying analysis of variance to the triiodothyronine and thyroxin data obtained by different laboratories using the same kit showed that most kits yielded significantly different measurements when used in different laboratories.
Determination of retinyl esters and retinol in serum or plasma by normal-phase liquid chromatography: method and applications.
Authors: Bankson D D , Russell R M , Sadowski J A
Published: January 2020

Retinol and retinyl esters are measured in serum or plasma samples by gradient, normal-phase, adsorption "high-performance" liquid chromatography, with ultraviolet detection at 325 nm. The four major circulating retinyl esters in humans (esters of palmitate, stearate, oleate, and linoleate) are coeluted as a single peak. Retinyl acetate is included as an internal standard, to correct for variable recovery. Retinol values so measured correlated well (r = 0.88) with those by a widely used reversed-phase chromatographic technique (Clin Chem 1983;29:708-12). The mean retinol concentration was 570 (SEM 17) micrograms/L and the mean for retinyl esters was 33 (SEM 4) micrograms/L as determined in samples from 88 fasting young adults. Concentrations of retinol in plasma as low as 50 micrograms/L can be detected in 100-microL samples, as can 10 micrograms of retinyl esters per liter. Using this method, we measured absorption of low doses of vitamin A, which may provide a more physiological approach to assessment of fat malabsorption. Additionally, the procedure proved useful for quickly screening for vitamin A toxicity. Major advantages include small sample size, direct injection of the extract ed sample without evaporation, rapid elution pattern, co-elution of major retinyl esters as a single peak, and low limit of detection.
Plasma lipase properties as related to pancreatic condition.
Authors: Arzoglou P L , Lessinger J M , Férard G
Published: January 2020

We examined the sensitivity to colipase of two types of lipase (EC 3.1.1.3) activity in plasma. Results were very similar for plasma lipase corresponding to that found in cases of acute pancreatitis and for swine pancreas lipase, whereas we found some differences between "pancreatitis lipase" and lipase from healthy subjects. Gel-filtration experiments suggest that the two forms of lipase in plasma have different relative molecular masses; moreover, their avidity for antibodies against human pancreatic lipase differs. Guided by these studies, we propose optimal conditions for nephelometry of "pancreatitis" lipase.
Direct homogeneous phosphoroimmunoassay for carbamazepine in serum.
Authors: Sidki A M , Smith D S , Landon J
Published: January 2020

In this "phosphoroimmunoassay," a phosphorescent label is used: erythrosin (tetraiodofluorescein). Its long-lived phosphorescence was detected after pulsed excitation in a time-resolved luminescence spectrometer. To achieve convenient open-atmosphere phosphorimetry in liquid solution at room temperature, we used sodium sulfite as an "in situ" chemical deoxygenator, to eliminate oxygen quenching of the excited triplet state. Time-resolved detection allows for complete rejection of short-lived background signals, including those from fluorescent or light-scattering components of biological fluids that can interfere in fluoroimmunoassays. We chose the antiepileptic drug carbamazepine (CBZ) and its active metabolite CBZ-10, 11-epoxide (CBZE) to demonstrate the development and validation of nonseparation assays based on quenching the phosphorescence of erythrosin-labeled drug upon binding to antibody. These two compounds cross reacted equally with the antiserum used; hence, we measured the activity of both in patients' sera. Alternatively, simple pre-treatment of the sample with acid destroys CBZE immunoreactivity and enables specific assay of CBZ.
Direct enzymic measurement of glycerides in serum and in lipoprotein fractions.
Authors: Kohlmeier M
Published: January 2020

A simple two-step procedure is now available for directly measuring triglycerides in whole serum and in lipoprotein fractions. I tested the performance of the assay, using pooled serum stored frozen, freshly prepared lipoprotein fractions, and pure glyceride standards. A parabolic concentration-response curve ensured linearity well beyond total glycerol concentrations of 10 mmol/L, but gave rise to misleading results for massively lipemic samples. Within-day CVs averaged 2.2% for the stored-frozen serum pools; mean day-to-day variation was 2.4%. Analytical recoveries of triglycerides, after lipoprotein fractionation, ranged between 101.9 and 103.7%. Aqueous glyceride standards gave results equivalent to between 95 and 105% of their glycerol content.
Determination of histamine concentrations in plasma by liquid chromatography/electrochemistry.
Authors: Harsing L G , Nagashima H , Duncalf D , Vizi E S , Goldiner P L
Published: January 2020

Histamine was extracted from deproteinized plasma with Amberlite CG 50 weak cation-exchange resin (analytical recovery of [3H]histamine, 60.5%). The eluate was evaporated and histamine in the redissolved sample was condensed with o-phthalaldehyde and 2-mercaptoethanol at pH 11.5. This adduct was separated by liquid chromatography under isocratic conditions and oxidized on a glassy carbon electrode at +0.4 V for electrochemical detection. 3-Methylhistamine was used as internal standard. As little as 0.45 pmol of standard histamine condensate was detected. The histamine concentration in 88 human plasma samples appeared to be normally distributed; its mean value was 7.20 (SD 2.61) nmol/L. Authentic and extracted histamine produced similar hydrodynamic voltammograms, and exogenous and endogenous histamine gave identical chromatographic characteristics with different mobile phases or different chromatographic columns. Standard and extracted histamine had similar degradation rates when samples were incubated with diamine oxidase (EC 1.4.3.6). Analytical recovery of known amounts of histamine added to pooled plasma was 97.7% (SD 22.3%). The inter- and intra-assay CVs for histamine determinations were 9.0% and 8.6%, respectively.
Immunoturbidimetric techniques for quantifying apolipoproteins CII and CIII.
Authors: Rifai N , Silverman L M
Published: January 2020

Immunoturbidimetric assays for determination of serum apolipoproteins CII and CIII (apo CII and CIII) were developed for use on the Cobas-Bio centrifugal analyzer with commercially available antisera and reference sera. Within-run and between-run imprecision (CVs) for apo CII was respectively 3.3 and 6.2%, and for apo CIII 2.75 and 5.2%. Addition to sera of as much as 50 g of hemoglobin or 0.15 g of bilirubin per liter did not interfere with determinations of apolipoproteins. Concentrations of apo CII and CIII were measured in sera from 40 normolipidemic and hyperlipidemic subjects by these immunoturbidimetric methods (x) and by radial immunodiffusion assays (y). Apo CII and CIII gave slopes of 0.93 and 0.86, y-intercepts of 7.4 and 9.5 mg/L, and correlation coefficients of 0.96 and 0.94, respectively. Reference intervals for the two apolipoproteins were established with sera from 100 normolipidemic subjects. The distribution of apo CII and CIII among the various lipoprotein fractions for normal subjects differed significantly (p less than 0.005) from that for hypertriglyceridemic subjects.
Estradiol receptors in human breast carcinomas assayed by use of monoclonal antibodies.
Authors: Duffy M J , O'Siorain L , Waldron B , Smith C
Published: January 2020

Our aim here was to compare a new enzyme immunoassay for estradiol receptors (ER) in breast cancer with a standard assay involving radiolabeled estradiol. A significant correlation was obtained between the standard binding assay and immunoassay (rs = 0.945, p less than 0.001, n = 100). Immunoreactive ER were also found in endometrial carcinomas but not in lung carcinomas, malignant melanomas, or basal cell carcinomas. Patients with breast cancers containing immunoreactive ER survived significantly longer after operation than patients whose tumor lacked immunoreactive ER. This immunoassay for ER is simpler than the binding assay and requires less time and tissue.
Two automated procedures for N-acetyl-beta-D-glucosaminidase determination evaluated for detection of drug-induced tubular nephrotoxicity.
Authors: Goren M P , Wright R K , Osborne S
Published: January 2020

We automated two procedures for determination of urinary N-acetyl-beta-D-glucosaminidase (NAG; EC 3.2.1.30) concentrations and evaluated their reliability for detecting drug-induced tubular damage in children receiving cisplatin, methotrexate, or ifosfamide. Results for 174 patient specimens correlated well (r = 0.98), but NAG concentrations determined by the m-cresolsulfonphthaleinyl (MCP) procedure were about 40% lower than those obtained with p-nitrophenyl-N-acetyl-beta-D-glucosaminide substrate. Dialysis and assay of 50 specimens disclosed no evidence of activators or inhibitors of enzymatic activity. Drugs and metabolites added to urine had negligible effect on NAG determinations; however, NAG was unstable in alkaline urine (pH greater than 8) associated with methotrexate therapy. Both procedures detect tubular damage equally well and neither requires laborious sample treatment. The MCP procedure, being more sensitive and not requiring a sample blank, is better suited for rapid automated assays. Comparisons of clinical data obtained by the two procedures require standardization against human NAG.
Assay of circulating 1,25-dihydroxyvitamin D involving a novel single-cartridge extraction and purification procedure.
Authors: Hollis B W
Published: January 2020

By use of a single-cartridge system, 1,25-dihydroxyvitamin D [1,25(OH)2D] is extracted and purified from a plasma or serum sample. Proteins are removed and 1,25(OH)2D is liberated from the sample with acetonitrile. The acetonitrile extract is applied to the nonpolar octadecylsilanol silica cartridge, in which 1,25(OH)2D is retained while polar compounds are eluted. Then by "phase-switching" on the same cartridge, 1,25(OH)2D is sufficiently resolved from other vitamin D metabolites and extraneous lipophilic compounds to allow its quantification by radioreceptor assay according to an established procedure. Mean (and SD) values for 1,25(OH)2D in serum of 29 normal, 27 chronic renal failure, and nine pregnant subjects were 28.2 (11.3), 10.9 (5.2), and 47.3 (12.9) ng/L, respectively. Results compared well with those of an established radioreceptor procedure. This procedure offers the advantage of a single rapid purification step not involving "high-performance" liquid chromatography or evaporation, under nitrogen, of polar solvents such as acetonitrile or methanol.
Can nutritional criteria help predict outcome in hospitalized patients?
Authors: Prabhakaran V M , Pujara S , Mills A J , Whalen V W
Published: January 2020

The following nutritional criteria were evaluated for their usefulness in predicting outcome in a prospective study of 66 randomly selected hospitalized patients with a variety of diagnoses: total protein, albumin, and transferrin concentrations in serum, creatinine height index, weight height index, phenylalanine/tyrosine ratio (Phe/Tyr), concentration of branched-chain amino acids in serum, and ratio of essential to nonessential amino acids in serum. The cases were followed from admission to discharge, and were classified into the following three groups: 43 "well"; 14 with "complications" but recovered; and nine "dead". Statistical analysis (Scheffe's s-test) demonstrated the means of "well" and "dead" groups to be different for total protein, albumin, transferrin, and Phe/Tyr. In individual patients the nutritional criteria, even for those with fatal outcome, were poor indicators of outcome. These nutritional criteria are useful in identifying hospitalized groups that are at maximum risk (i.e., death), but are much less useful for individual patients.
Lentil-lectin-reactive alpha-fetoprotein in the differential diagnosis of benign and malignant liver disease.
Authors: Buamah P K , Harris R , James O F , Skillen A W
Published: January 2020

Affinity chromatography of serum on lentil lectin bound to Sepharose 4B has been used to identify different forms of alpha-fetoprotein in serum of patients with liver disease. We studied eight patients with non-malignant liver disease, finding that 7-15% of the serum alpha-fetoprotein bound to the lectin. In contrast, for 15 patients with malignant liver disease, 25-83% of the serum alpha-fetoprotein bound to the lectin. Evidently, this simple technique can be used effectively to differentiate these two conditions.
Nephelometric assay of apolipoprotein A-I with a centrifugal analyzer.
Authors: Hanson N Q , Freier E F
Published: January 2020

We developed an automated immunonephelometric assay for quantification of human apolipoprotein A-I (apo A-I) with a fluorescence light-scattering microcentrifugal analyzer. The presence of polyethylene glycol and Tween 20 in the reaction mixture ensures maximum exposure of the antigenic sites of the apoprotein so that immune complex formation occurs more rapidly (reaction is complete within 2 min) and to a greater extent. Lipemia and hemolysis do not interfere with the measurement of apo A-I. The method requires only 10 microL of specimen and is fast and easy to perform. Results vary linearly with apo A-I concentrations to 2.5 g/L. Assay precision (CV) was 3.1% for a specimen with an apo A-I concentration of 1.45 g/L, and the lower limit of detection was 0.15 g/L. Values for a candidate Reference Material agree well with those reported in an international survey (Clin Chem 1985;30:223-8).
Inaccurate measurement of a polymeric IgA myeloma protein by nephelometric and fluorometric instrumentation.
Authors: Levinson S S , Goldman J O , Markyvech L , Nathan L E
Published: January 2020

The concentration of IgA in a serum was 5.99 g/L as assayed nephelometrically with reagent from one company, but varied between 5 and 3 g/L (for sixfold and 36-fold dilutions, respectively) without giving a definitive answer when assayed with reagent from another source. Immunofixation electrophoresis indicated an IgA lambda monoclonal protein of 45 g/L. Radial immunodiffusion showed two components, having a total concentration of 41 g/L. By fluorometry the IgA was 3.1 g/L. Increasing the dilution caused the (dilution-corrected) lower values to increase. Although the most frequent cause of such discrepant findings is an IgA2 myeloma, which occurs in about one of every 100 myeloma cases, Ouchterlony double diffusion indicated the major component to be IgA1. A polymer, Mr 670,000, was identified by column chromatography. Contrary to the usual behavior of polymers assayed with radial immunodiffusion, which underestimates their concentration, this polymer reached equivalency in agreement with its true concentration as assayed by the Mancini-Heremans technique.
Detection of complement activation in immune complex diseases: six methods compared.
Authors: Sun T , Stagias J
Published: January 2020

We compared the performance of six complement tests: electrophoresis, immunofixation, immunoelectrophoresis, and nephelometric quantifications of C3, C4, and C3d. We used 123 blood samples from 60 control subjects and 63 patients with immune complex diseases: systemic lupus erythematosus, idiopathic thrombocytopenic purpura, rheumatoid arthritis, acquired immunodeficiency syndrome, renal diseases, vasculitis, cryoglobulinemia, Gram-negative bacteremia, Hashimoto's thyroiditis, rheumatic heart disease, malaria, and chronic active hepatitis. Immunofixation and quantification of C3d were better for detecting complement activation, their sensitivity rates (90.5% and 89.3%, respectively) being higher than those of the other tests studied. Immunofixation is a relatively simple and inexpensive test, provides good resolution of protein bands, and yields results that are easily quantified with a densitometer. Nephelometry of C3d provides more rapid and accurate quantitative results than immunofixation, but commercial reagents are not yet available. The causes of false-positive results in complement tests and the mechanisms of complement activation in AIDS are also discussed.
Artefactual increase in serum thyrotropin concentration caused by heterophilic antibodies with specificity for IgG of the family Bovidea.
Authors: Bartlett W A , Browning M C , Jung R T
Published: January 2020

A 19-year-old white woman presented with symptoms compatible with mild hyperthyroidism and biochemical evidence suggestive of autonomous thyrotropin (TSH) secretion. Intensive investigation of the pituitary-thyroid axis suggested that the basal concentrations of TSH were artefactually increased owing to heterophilic antibodies in the patient's serum with a broad specificity for immunoglobulin class G of the family Bovidea. These heterophilic antibodies complexed with the ovine antisera to human thyrotropin that are used in the RIA system, in particular blocking the binding of TSH but also partly blocking interaction with the second antibody. When TSH was measured immunometrically or by an RIA with TSH-specific antisera of rabbit origin, the concentrations measured were within the appropriate reference intervals. The blocking effect can be overcome by including large quantities of non-TSH-specific ovine IgG in assay incubation mixtures. Interference of this type is generally not appreciated and its incidence is poorly characterized, but it may have implications for any method in which antibodies are used as reagents.
Homogeneous, liposome-based assay for total complement activity in serum.
Authors: Bowden D W , Rising M , Akots G , Myles A , Broeze R J
Published: January 2020

This is a rapid, homogeneous, liposome-based assay for total complement activity in human serum. Liposome-encapsulated enzyme is unmasked by the action of complement on liposomes carrying surface-bound immune complexes. The amount of unmasked enzyme, proportional to the concentration of added complement, is quantified by measuring the absorbance of enzymically produced product at 410 nm. Complement activity in serum samples is extrapolated from a standard curve generated from dilutions of a guinea pig serum containing a known activity of complement. Interassay CVs were less than 7.0% and intra-assay CVs less than 2.8% for serum pools with complement activities spanning the normal range. Test results correlate as well with those of the hemolytic complement test (r = 0.80) as the latter correlates with itself (r = 0.82), and also correlate reasonably with measurements of complement components C3 (r = 0.62) and C4 (r = 0.74). Values for a normal population are reported. Advantages of this test include stability of reagents, speed, accuracy, simplicity, and avoidance of radioisotopes.
Characterization of lysosomal acid phosphatase from normal and malignant mammary tissue.
Authors: Podhajcer O L , Filmus J E , Mordoh J
Published: January 2020

Acid phosphatase (EC 3.1.3.2) isoenzyme 3 was purified from normal and malignant human mammary tissue and its properties in each were compared. The relative molecular mass of each was 53 000, as measured by sodium dodecyl sulfate gel electrophoresis. Several phosphomonoesters are good substrates for the isoenzymes, whereas organic and inorganic pyrophosphates and phosphoryl choline are hydrolyzed very slowly or not detectably. The optimum pH for interaction of these isoenzymes with p-nitrophenyl phosphate as substrate ranges from 3.5 to 4.5. L-(+)-Tartrate is a very strong inhibitor, Ki = 0.028 +/- 0.04 mmol/L (mean +/- SE), as are mercuric and fluoride ions in low concentrations. We conclude that type 3 isoenzymes obtained from normal and malignant tissue are very similar, though the malignant tissue appears to have a greater proportion of this type than does normal tissue.
Three methods compared for determination of pancreatic and salivary amylase activity in serum of cystic fibrosis patients.
Authors: Wolf R O , Hubbard V S , Gillard B K , Kingman A
Published: January 2020

We evaluated three methods for serum amylase (EC 3.2.1.1) isoenzymes to determine whether they are interchangeable and to test their ability to discriminate between cystic fibrosis patients with and without pancreatic insufficiency. One method involved salivary amylase inhibitor (O), and two were polyacrylamide gel electrophoresis separations differing in method of detection--either direct zymogram (G) or gel slicing followed by activity estimates per slice (W). Results for percentage pancreatic amylase differed significantly. Reproducibility for percentage pancreatic amylase was high, moderate, and low (r = 0.95, 0.53, and 0.02) for methods G, O, and W, respectively; moderate (r = 0.60) among the three methods; and moderate between pairs. Therefore, this result for a subject must be considered relative to the method used in its determination. The clinical diagnosis of pancreatic insufficiency was verified by 77.8%, 83.3%, and 94.4% correct classification rates for methods O, W, and G, respectively. Evidently, method G is the most efficient and may be the method of choice for measuring serum amylase isoenzymes in cystic fibrosis.
Protein markers of nutrition status as related to sex and age.
Authors: Sachs E , Bernstein L H
Published: January 2020

We assessed age- and sex-related variation in those proteins commonly measured to evaluate protein catabolic losses in patients in acute care. We determined concentrations of iron and iron-binding capacity, transferrin, albumin, prealbumin, and retinol-binding protein in sera from 158 healthy blood donors and 48 hospitalized patients, then grouped the data according to age (by decade) and sex. There was no significant variation in either category. For the total nondiseased population the concentrations of three proteins (means SD, and range) were: transferrin, 2760, 510, 1740-3780 mg/L (population CV 18.5%); prealbumin, 296, 49, 200-390 mg/L (CV 16.6%); retinol-binding protein, 60, 127, 35-85 mg/L (CV 21.2%). Prealbumin and retinol-binding protein concentrations were highly correlated (r = 0.803). Because prealbumin can be easily monitored and its assay is subject to few interferences, we conclude that determination of prealbumin is suitable for assessing the existence and severity of nutritional metabolic deficits.
Substrate-Leash Amplification with Ribonuclease S-Peptide and S-Protein
Authors: Ehrat Markus , Cecchini Douglas J , Giese Roger W
Published: January 2020

p 1628, Fig. 6: Although faint, there is a band at the origin in lane g.

p 1656: The accompanying figure should be substituted for the Figure 2 shown on page 1656, a figure that was to have been deleted. The figure legend is unchanged.

p 1705: The second paragraph in the left column should replace the third paragraph of the Discussion. Thus the authors find it "likely...that the principal alkali-labile oxalate precursors in urine are ascorbate and some of its metabolites...."

p 1927: The name of the author of a book review, Robert Rej, was omitted.

p 2014: On line 7, the 95 percentile interval for plasma ammonia should be 16-53 µmol/L, as correctly stated in the Abstract.

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Assay performance and tracer properties for two analog-based assays of free triiodothyronine.
Authors: Wilkins T A , Midgley J E , Stevens R A , Caughey I , Barron N
Published: January 2020

We determined binding characteristics of the triiodothyronine (T3) analog tracer used in the Amerlex and Amerlex-M FT3 radioimmunoassay for the three endogenous binding proteins in serum: thyroxin-binding globulin (TBG), thyroxin binding prealbumin (PA), and albumin. Both T3 and its analog bind to the same sites on TBG and PA. However, the analog has significantly lower association constants (1.0% and 3.8%, respectively, of T3 binding affinity) and it binds to different sites on albumin. Analog binding is characterized by two (weak) specific binding sites [K = 0.46 (SD 0.03) X 10(5) L/mol]; T3 is bound at about 28 very weak, nonspecific sites [K = 0.41 (SD 0.03) X 10(4) L/mol]. Sera from healthy subjects with a wide range of concentrations of binding proteins showed no interference from analog binding in the FT3 assay. In contrast, in vitro studies of albumin binding revealed a weak dependence of both assays on albumin concentration (0.05 pmol of FT3 per gram of albumin per liter), an interference probably unimportant for most laboratory samples. Nonesterified fatty acids (NEFA) and the T3 analog apparently bind to different sites on albumin; thus the Amerlex FT3 assay is insensitive to moderately increased concentrations of NEFA in serum.
Graphical comparisons of interferences in clinical chemistry instrumentation.
Authors: Glick M R , Ryder K W , Jackson S A
Published: January 2020

Instrument- and analyte-specific interferences can be produced by adding known concentrations of potentially interfering substances to serum from healthy volunteers. Analytical results are expressed as a percentage of the original (unaffected) result. Graphical displays of the transformed data document the conditions under which erroneous results would be probable for specimens containing the additive. If several analytical systems are available, one can make an informed choice of which to use for a particular analysis by comparing the appropriate graphical information. Comparisons of such displays of data from newer systems being considered for purchase may facilitate decisions regarding laboratory instrumentation.
Circulating antibodies to mouse monoclonal immunoglobulins in normal subjects--incidence, species specificity, and effects on a two-site assay for creatine kinase-MB isoenzyme.
Authors: Thompson R J , Jackson A P , Langlois N
Published: January 2020

With a two-site CK-MB assay, we screened serum samples from 1008 blood donors for the presence of antibodies to mouse monoclonal immunoglobulin. These antibodies were capable of cross-linking the labeled antibody with the solid-phase antibody in the two-site assay, thus generating a falsely high apparent CK-MB concentration. In 92 (9.12%) of the blood donors tested, apparent CK-MB concentrations of 10-1000 micrograms/L decreased to less than 3 micrograms/L when re-assayed with non-immune mouse serum (10 mL/L) included in the assay reagent. We tested the ability of non-immune sera from other animal species to lower the concentration of apparent CK-MB in 58 of the 92 samples. Bovine and ovine serum were almost as effective as mouse serum; feline, canine, and rabbit serum were less effective. Of the samples tested, 12% (1.1% of the original population screened) showed apparent CK-MB values that either were not depressed by bovine serum or were only partly depressed. We discuss the possible etiology of these antibodies in normal subjects and recommend that all mouse monoclonal two-site assays should contain non-immune mouse serum (or a suitable "irrelevant" mouse monoclonal antibody) to prevent false-positive results.
Direct ultraviolet method for enzymatic determination of uric acid, with equilibrium and kinetic data-processing options.
Authors: Dilena B A , Peake M J , Pardue H L , Skoug J W
Published: January 2020

We developed and evaluated a direct ultraviolet method for the enzymatic determination of uric acid in serum, plasma, or urine, without deproteinization of sera and plasma. Equilibrium and nonlinear curve-fitting kinetic options are evaluated and compared, and results of the proposed method are compared with those of a candidate Reference Method. All data-processing options yield a linear relation for absorbance and concentration of uric acid between 0.1 and 2 mmol/L; with the equilibrium option, results are linear to 5 mmol/L. For 100 plasma samples, results correlate well between the proposed method (y) and a reference method (x): y = 0.99x - 0.002 mmol/L. Between-run imprecision is about 2.3%, and interference by hemolyzed, icteric, or lipemic specimens or specimens containing high concentrations of xanthine or paraproteins is minimal. The kinetic option with a data-processing range of 100 s or longer yields results that correlate well with the equilibrium method: y = 1.006x + 0.002 mmol/L (n = 118). For 20 urine samples processed by the proposed (y) and a reference (x) methods, y = 1.04x + 0.038 mmol/L.
A sensitive and practical immunoradiometric assay of thyrotropin.
Authors: Helenius T , Tikanoja S
Published: January 2020

We describe a two-site immunoradiometric assay for thyrotropin (TSH) in serum, based on use of two monoclonal antibodies directed against two separate antigenic determinants on the TSH molecule. One antibody is immobilized on polystyrene beads; the other is radioiodinated by a modified Chloramine T method. The detection limit of the assay is 0.02 milli-int. unit/L. The working range (CV less than 10%) is from 0.1 to greater than 50 milli-int. units/L. The log mean concentration of TSH in sera collected from 100 euthyroid subjects between 08:00 and 11:00 hours was 1.9 milli-int. units/L, the range 0.4-5.4 milli-int. units/L. Values for hyperthyroid patients and thyroid-cancer patients being treated with thyroxin were much lower than those for euthyroid persons. Results by this new assay correlated excellently with those by our conventional radioimmunoassay (r = 0.99) and also with a sensitive immunofluorometric TSH method (Delfia TSH) (r = 0.99).
Evaluation of "HemoCue," a new device for determining hemoglobin.
Authors: von Schenck H , Falkensson M , Lundberg B
Published: January 2020

Hemoglobinometry according to the International Committee of Standardization in Hematology (ICSH) suffers from imprecision related to high sample dilution and from potential errors owing to sample turbidity. We have evaluated a new instrument, "HemoCue," that measures hemoglobin at two wavelengths as azide methemoglobin, without dilution. The HemoCue method is superior to the ICSH method: by correction for turbidity, it avoids false hemoglobin readings that may arise from hyperlipemia or some large M-component of the immunoglobulin M class. We find the equipment suitable for use in outpatient units.
Rapid electrophoretic determination of neuron-specific enolase isoenzymes in serum.
Authors: Viallard J L , Ven Murthy M R , Dastugue B
Published: January 2020

This assay procedure for each of the two neuron-specific enolases (alpha gamma and gamma gamma) and the non-neuronal enolase (alpha alpha) in serum involves two steps: electrophoretic separation of the three isoenzymes--alpha alpha, alpha gamma, and gamma gamma--on cellulose acetate, and bioluminescence measurement of total enolase activity. From these data, the activity concentrations (U/L) of the three isoenzymes in serum are calculated. Both measurement steps are based on the enzymatic activity of enolase and thus differ from the immunological methods currently in use, which require the availability of specific antibodies. The method is rapid (approximately 30 min for both steps) and requires only 10 microL of serum for the complete analysis. Studies of normal children and adults, and of patients suffering from neuroblastoma and small-cell lung cancer, show that it is suitable for clinical use. Furthermore, the fact that both neuron-specific isoenzymes of enolase can be systematically separated is an advantage over immunological techniques in determining isoenzyme patterns for pathological samples.
Interaction of cisplatin and carboplatin with sodium thiosulfate: reaction rates and protein binding.
Authors: Elferink F , van der Vijgh W J , Klein I , Pinedo H M
Published: January 2020

Toxicity of cisplatin can be decreased by concomitant administration of sodium thiosulfate, which perhaps chemically inactivates this platinum compound. We studied the disappearance of cisplatin and carboplatin in aqueous solutions of thiosulfate at 37 degrees C by means of liquid chromatography. At initial concentrations that were similar to therapeutic concentrations in plasma, both drugs disappeared, with half-lives of 66 and 537 min for cisplatin and carboplatin, respectively. At higher thiosulfate concentrations, as found in urine, the respective half-lives were 3.7 and 33.8 min. These values suggest that direct chemical interaction in the plasma compartment has limited therapeutic consequences, whereas the anti-toxic effect of thiosulfate might be explained by the rapid inactivation of cisplatin in the kidneys. Reaction products of cisplatin and thiosulfate bound instantaneously and mainly reversibly to plasma proteins. Protein-bound cisplatin was not released by added thiosulfate--which may explain why thiosulfate, to be effective, must be given in advance of and during cisplatin administration.
Rapid, competitive enzymoimmunoassay for albumin in urine.
Authors: Chesham J , Anderton S W , Kingdon C F
Published: January 2020

In this solid-phase competitive enzymoimmunoassay for albumin in human urine, antiserum to human serum albumin labeled with horseradish peroxidase (EC 1.11.1.7) is incubated with solid-phase-bound human serum albumin in the presence of sample or standard. Results obtained correlate well (r = 0.96) with those of an established fluoroimmunoassay. The present assay covers the range 0.9 to 200 mg/L and can be performed within 1 h. These characteristics, together with the simplicity of the assay protocol, make it very useful for monitoring low concentrations of albumin in urine. Detection of such minimal albuminuria allows initiation of therapy that may prevent development of clinical proteinuria and associated diabetic nephropathy.
Dry- and wet-ashing techniques compared in analyses for zinc, copper, manganese, and iron in hair.
Authors: Friel J K , Ngyuen C D
Published: January 2020

Preparation of hair specimens for trace-metal analyses is routinely done by wet- or dry-ashing. Wet-ashing is more time consuming than dry-ashing and can be dangerous. We wished to determine if dry-ashing was a suitable alternative to wet-ashing with HClO4:HNO3 or HNO3 alone in preparing hair for measurement of zinc, copper, iron, and manganese by atomic absorption spectroscopy. Concentrations of Zn, Cu, and Mn were not differently affected in hair that was dry- or wet-ashed. Analytical recovery of these elements added to hair samples ranged from 102 to 108%; day-to-day CVs were less than 5%. Fe was lost during dry-ashing of hair, and wet-ashing with HNO3 produced results for Fe comparable with those obtained with HClO4:HNO3. Therefore we recommend dry-ashing of hair to be analyzed for Zn, Cu, and Mn, but wet-ashing with HNO3 for assays of Fe.
Quantitative homogeneous enzyme immunoassays for amitriptyline, nortriptyline, imipramine, and desipramine.
Authors: Pankey S , Collins C , Jaklitsch A , Izutsu A , Hu M , Pirio M , Singh P
Published: January 2020

We describe specific EMIT homogeneous enzyme immunoassays for amitriptyline, nortriptyline, imipramine, and desipramine in patients' serum samples. Before analysis, an easily performed extraction step involving the use of 500 microL of sample and a 1-mL disposable column eliminates cross-reacting polar metabolites. The range of the standard curve for the first three drugs is 25 to 250 micrograms/L, and for desipramine is 50 to 500 micrograms/L. Within-run and between-run CVs are less than 10% throughout the range of the assays. Results for patients' samples obtained by this method and by "high-performance" liquid chromatography compare well, showing a slope range of 0.94-1.04 and correlation coefficients ranging from 0.93 to 0.96, depending on the assay.
Prevalence of antibodies to HTLV-III in quality-assurance sera.
Authors: Howanitz P J , McBride J H , Kliewer K E , Rodgerson D O
Published: January 2020

We tested 146 clinical-laboratory quality-assurance sera for antibodies to human T-lymphotropic virus III (HTLV-III). Of 127 human-based samples, 39 (31%) were positive by an immunoenzymometric assay (IEMA). Samples of human origin that gave IEMA reactivity included four of 10 ethylene glycol-based (liquid) samples, two of six in-house pools of fresh sera, and 32 of 111 lyophilized samples. All 19 bovine-based samples were negative. Antibodies to HTLV-III in 16 samples were remeasured by a second IEMA and the Western blot technique. All assays detected antibody reactivity in four of the 16 samples; however, results of the second IEMA and the Western blot agreed best. We report large discrepancies between assay results when laboratory reagents are tested for HTLV-III antibodies, and find that many quality-assurance samples containing human sera have measurable IEMA reactivity for HTLV-III antibody. Reactivity in these assays indicates the presence of antibody, not viral infectivity.
Association of apolipoprotein E polymorphism, low-density lipoprotein cholesterol, and coronary artery disease.
Authors: Lenzen H J , Assmann G , Buchwalsky R , Schulte H
Published: January 2020

We determined the frequencies of genetic apolipoprotein E isoforms in 570 survivors of myocardial infarction, all with demonstrable coronary heart disease, as compared with 624 healthy persons. In controls, E-4/E-3 heterozygosity was associated with total cholesterol concentrations of 1985 (SD 364) mg/L and low-density lipoprotein (LDL)-cholesterol concentrations of 1306 (SD 332) mg/L. Significantly lower values, 1811 (SD 312) mg/L and 1121 (SD 274) mg/L, respectively, were observed for E-3/E-2 heterozygous persons. In survivors of myocardial infarction, the respective values were significantly higher than in controls, differing between E-4/E-3 and E-3/E-2 heterozygous patients by 233 and 220 mg/L, respectively. Moreover, E-4/E-3 heterozygosity was accompanied by earlier age of myocardial infarction (48.8 +/- 7.4 years) as compared with E-3/E-2 heterozygosity (53.4 +/- 6.9 years) and E-3/E-3 homozygosity (51.2 +/- 7.7 years). Evidently, apolipoprotein E polymorphism can contribute to total and LDL-cholesterol concentrations in serum, thereby affecting risk of coronary heart disease and myocardial infarction.
Liquid-chromatographic measurements of inosine, hypoxanthine, and xanthine in studies of fructose-induced degradation of adenine nucleotides in humans and rats.
Authors: Kurtz T W , Kabra P M , Booth B E , Al-Bander H A , Portale A A , Serena B G , Tsai H C , Morris R C
Published: January 2020

We applied a sensitive, precise liquid-chromatographic method of analysis for inosine, hypoxanthine, and xanthine to the study of fructose metabolism in humans and in rats. In the rat, intravenous loading with fructose induced, within minutes, substantial increases in the concentrations of inosine, hypoxanthine, and xanthine in plasma and urine. In plasma, these concentrations peaked after 5 min, then practically disappeared within 10 min. As expected, the fructose-induced increase in hypoxanthine was greatly amplified by pretreating the rats with allopurinol, an inhibitor of xanthine oxidase. In a healthy human subject, intravenous administration of fructose also induced prompt, substantial, and rapidly reversing increases in the concentrations of these metabolites of adenine nucleotides in plasma. The finding that fructose induced almost-immediate increases in the plasma concentrations of inosine, hypoxanthine, and xanthine is consistent with previous studies in rats, in which parenteral administration of fructose induced almost-immediate decreases of total adenine nucleotides (ATP + ADP + AMP) in the liver, and increased concentrations of uric acid and allantoin in the plasma.
Two methods compared for measuring LD-1/total LD activity in serum.
Authors: Bernstein L H , Scinto P
Published: January 2020

We present evidence for the utility of an improved assay for the activity of lactate dehydrogenase (EC 1.1.1.27) isoenzymes 1 and 2 in serum, involving inhibition of the H-subunit of LD by pyruvate at pH 7.1. Results correlate well with the LD-1/total LD ratio as evaluated by immunological assay and, as an index to infarct, the method is superior to either the change in CK-MB activity or to the LD-1 activity or to a combination of these tests, as is the percentage of LD-1 to total LD activity. Moreover, the percentage inhibition of LD activity by pyruvate may have an advantage over other methods of isoenzyme fractionation because of its smaller population CV for patients with acute myocardial infarction than is true of other methods. We also demonstrate how, using a linear discriminant analysis, we compared this method with alternative methods. We determined that evaluation of CK-MB isoenzyme contributes no information in addition to that obtained from the LD-1 isoenzyme.
Measurement of urinary free 20 alpha-dihydrocortisol in biochemical diagnosis of chronic hypercorticoidism.
Authors: Schöneshöfer M , Weber B , Oelkers W , Nahoul K , Mantero F
Published: January 2020

Using liquid chromatography, we estimated the urinary excretion of 20 alpha-dihydrocortisol (20-DH) and urinary free cortisol (UFC) in normal subjects and in 40 patients with Cushing's syndrome of different etiologies. The median normal excretion rate (nmol/24 h) was 174 for 20-DH and 68 for UFC, the 20-DH/UFC ratio thus being 2.55. For patients with Cushing's syndrome, the excretion rate was 1798 for 20-DH and 298 for UFC, the ratio 6.03. We evaluated the effect of acute stimulation of adrenal secretion on 20-DH and UFC by administering corticotropin to six normal subjects. After such stimulation, the excretion rate was 566 for 20-DH and 1238 for UFC (ratio 0.45). Whereas 20-DH excretion rate exceeded the normal range in all patients, six patients had normal or even below-normal values for UFC excretion. Evidently, measurement of urinary 20-DH is a better test for chronic hypercorticoidism than is measurement of urinary UFC, and chronic hypercorticoidism can be differentiated from the acute state by the 20-DH/UFC ratio.
Reducing the artifacts produced by impure antisera in immunoblots of low-molecular-mass proteins in urine.
Authors: Perini J M , Dehon B , Marianne T , Klein A , Roussel P
Published: January 2020

Immunoblots of several urinary low-molecular-mass proteins can be very useful in investigations of pathological proteinuria. However, use of certain commercial antisera in such procedures leads to artifacts corresponding to nonspecific bands; e.g., immunoglobulins from nonimmunized rabbit serum may bind to human urinary proteins, and this binding is not inhibited by Triton X-100. We have developed a procedure to improve the specificity of detection of urinary low-Mr proteins separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, by immunoblotting with commercial antisera: we treat the protein blot with a mixture of mercaptoethanol and sodium dodecyl sulfate before incubation with the first antiserum. This allows direct use of commercial antisera without prior absorption of contaminating antibodies.
Liquid-chromatographic determination of isoenzymes of alkaline phosphatase in serum and tissue homogenates.
Authors: Schoenau E , Herzog K H , Boehles H J
Published: January 2020

We describe a new method for separating alkaline phosphatase (AP) isoenzymes by means of "high-performance" liquid chromatography. Isoenzymes are eluted from the column (Mono Q HR 5/5, a strong anion-exchanger) with a stepwise gradient of LiCl. The isoenzymes originating from small intestine, bone, liver, and bile were identified by use of tissue homogenates, pathological sera, and heat inactivation.
Various methods for determining urinary choriogonadotropin evaluated for the early diagnosis of ectopic pregnancy.
Authors: Buck R H , Norman R J , Reddi K , Moodley J , Joubert S M
Published: January 2020

We evaluated the accuracy, sensitivity, specificity, and performance characteristics of seven methods for determining urinary choriogonadotropin in the early diagnosis of ectopic pregnancy in 46 patients with gynecological emergencies. The kits examined included immunoenzymometric assays (Tandem Icon hCG, Model Plus, Diapreg-25, Pregnastick, Nimbus) and reverse hemagglutination inhibition assays (NeoPregnosticon 75 Duoclon, Pregtest). We found immunoenzymometric assays to be the most sensitive procedures (lowest detection limits) for qualitatively detecting hCG secreted by ectopic pregnancy. We concluded that the Tandem Icon best meets our criteria and we advocate its use in the emergency room or ward as the first-line investigation of ectopic pregnancy. In addition, the use of Diapreg-25 has many theoretical advantages as an extremely sensitive index of choriogonadotropin status because of its ability to detect very low concentrations of beta subunit.
Liquid chromatography used in diagnosis of a rare hemoglobin combination: hemoglobin S/LeporeBoston.
Authors: Wessels R A , Rogers B B , Ou C N , Alcorn R , Buffone G J
Published: January 2020

"High-performance" liquid chromatography (HPLC), applied to hemoglobin analysis, is decidely more sensitive and gives better resolution than do routine electrophoretic methods. Here we present a case with a rare double heterozygote hemoglobin S/LeporeBoston, originally diagnosed as homozygous hemoglobin S by routine electrophoretic methods. Using a gradient elution weak cation-exchange HPLC technique, we could separate hemoglobin S and hemoglobin LeporeBoston and make the correct diagnosis. This case demonstrates how HPLC can be a useful adjunct to routine electrophoresis.
Exocrine pancreatic function as determined in a same-day test with use of bentiromide and p-aminosalicylic acid.
Authors: Berg J D , Chesner I M , Allen-Narker R A , Buckley B M , Lawson N
Published: January 2020

We describe a new approach to the bentiromide test of exocrine pancreatic function, p-Aminosalicylic acid (PAS), a compound closely related to the bentiromide fragment p-aminobenzoic acid (PABA), is used as a marker of the pharmacokinetic behavior of PABA to derive a PABA excretion index. This index is identical to that derived with [14C]-PABA. Concentrations of both PABA and PAS are measured in urine by "high-performance" liquid chromatography, which avoids the drug interferences encountered with established assays of PABA. We discuss the practical and diagnostic advantages of this new approach to the bentiromide test.