bluuebunny/crossref_metadata_2025 huggingface dataset:
Apolipoproteins C-II and C-III in serum quantified by zone immunoelectrophoresis.
Authors: März W , Schenk G , Gross W
Published: January 2020

Zone immunoelectrophoresis assays specific for apolipoprotein C-II and C-III have been developed. These simple, accurate, reproducible, and sensitive methods present valid alternatives to conventional immunoassays. In fasting normolipidemic men and women the concentrations of apolipoprotein C-II and C-III were 49 (SD 25) mg/L and 124 (SD 60) mg/L, respectively, with no sex-related differences for either apolipoprotein. The frequency distribution of apolipoprotein C-II was skewed to the right, whereas apolipoprotein C-III was bimodally distributed. Concentrations of each apolipoprotein correlated well with one another and with that of serum triglycerides, but there was virtually no correlation between the apolipoprotein C-II to C-III mass ratio and the concentration of triglycerides. Apolipoprotein C-III, but not apolipoprotein C-II, was statistically associated with total cholesterol.
Highly sensitive qualitative methods for serum choriogonadotropin (hCG): clinical specificity studies.
Authors: Bandi Z L , Schoen I , DeLara M
Published: January 2020

We screened six highly sensitive kits, designed for serum pregnancy tests, for false-positive results. The two best were then evaluated more extensively. The "BETA-hCG MAIA-clone" (I) and the "TANDEM ICON" (II) kits gave only negative results for 100 sera from men at 5, 10, and 25 int. units/L (1st IRP). Of 100 serum specimens from post-menopausal women three and 10 were hCG positive by the II and the I reagents, respectively, but only at the 5 int. units (1st IRP) of hCG per liter level of sensitivity. At 10 and 25 int. units/L, all specimens were negative by both tests. The manufacturers of these kits recommend pregnancy testing only at the 25 int. units/L level of analytical sensitivity. By quantitative methods, hCG concentrations in the II positive samples ranged from 6 to 20 int. units/L (1st IRP) and lutropin concentrations were between 130 to greater than 150 int. units/L. The medical records of the corresponding patients did not support the presence of trophoblast or any other hCG-secreting tissues. During 15 months of routine use of the II reagents at an analytical sensitivity of 25 int. units/L (1st IRP) hCG for pregnancy testing (greater than 4000 serum specimens from pre-menopausal women), the staff has not reported to us any suspected false-positive findings.
Hypothermic myxedema coma erroneously diagnosed as myocardial infarction because of increased creatine kinase MB.
Authors: Nee P A , Scane A C , Lavelle P H , Fellows I W , Hill P G
Published: January 2020

As is well recognized, activities of creatine kinase (CK, EC 2.7.3.2) and lactate dehydrogenase (EC 1.1.1.27) in plasma may be substantially increased in hypothyroidism. We emphasize here that an increase and decrease in CK-MB isoenzyme, characteristic of acute myocardial infarction, can occur in hypothermic myxedema coma without myocardial infarction.
Postsynthetic modification of human enolase isoenzymes.
Authors: Rigiani N R , Wevers R A , Rijk E , Soons J B
Published: January 2020

The original form of beta beta enolase (EC 4.2.1.11) in tissue is modified to two more electrophoretically distinct forms when incubated with human serum. The three postsynthetic forms are designated beta beta 3, beta beta 2, and beta beta 1, in order of increasing anodal mobility and increasing modification. Serum and carboxypeptidases A and B all produce identical modifications of beta beta enolase but exhibit very different pH-activity profiles. A purified human serum protein previously named "modifying protein," which is responsible for the modification of creatine kinase-M and alpha-enolase subunits, modifies beta beta enolase and also has a pH-activity profile identical to that for serum. Thus we conclude that the modifying protein is not identical to either carboxypeptidase A or B; it may, however, be an as-yet-undescribed carboxypeptidase. With increased modification, both alpha alpha and beta beta enolase decrease in apparent activation energy; gamma gamma enolase shows no evidence of modification, and its apparent activation energy remains stable. Measurement of activation energy is an easy tool for screening for postsynthetic modifications in an enzyme.
Diffuse reflectance technique for infrared analysis of urinary calculi.
Authors: Berthelot M , Cornu G , Daudon M , Helbert M , Laurence C
Published: January 2020

We investigated the application of diffuse reflectance infrared Fourier transform spectroscopy to analysis of urinary calculi and compared its operation with that of older sampling techniques (pellet, mull, and attenuated total reflectance). The new method requires shorter sample preparation time and less sample (30 micrograms). Quantitative measurements are easier. Because of the additivity of the Kubelka-Munk functions, a quasi-exhaustive collection of infrared spectra of mixtures of possible components of stones can be compiled, facilitating a computerized intrepretation of infrared spectra of urinary calculi.
Reflotron assays of alanine aminotransferase and gamma-glutamyltransferase in whole-blood samples evaluated.
Authors: James D R , Price C P
Published: January 2020

We evaluated the Reflotron (Boehringer Mannheim) system for measuring activities of alanine aminotransferase (EC 2.6.1.2) and gamma-glutamyltransferase (EC 2.3.2.2). Within- and between-day precision were comparable with conventional analytical methods. The linear range of the methods extended to more than 40-fold the upper limit of the reference range. The methods were not influenced by moderate changes in blood rheology and also tolerated some variation in sample volume applied. We consider these methods to be suitable for use in satellite or physicians' office laboratories (with appropriate training of operators), and they can produce results that agree satisfactorily with those determined in routine laboratory practice.
Interference by anti-immunoglobulin G antibodies in immunoradiometric assays of thyrotropin involving mouse monoclonal antibodies.
Authors: Zweig M H , Csako G , Benson C C , Weintraub B D , Kahn B B
Published: January 2020

"Sandwich"-type assays are subject to positive interference by the patient's "heterophile" antibodies. If present, these bind to the animal immunoglobulins in the assay reagents, forming artefactual sandwiches indistinguishable from those formed with the analyte itself. Immunoglobulins from non-immunized animals, added to the assay reagents, can diminish this effect by blocking the patient's antibodies. Elsewhere, we studied several patients with anti-mouse immunoglobulin activity, whose serum gave spuriously high results for thyrotropin (TSH) concentrations. Here we have studied this phenomenon by adding, to pooled zero-TSH serum, antibodies to mouse, goat, and horse immunoglobulins and then assaying TSH by several other sandwich-type assays involving mouse monoclonal antibodies. Assays not supplemented with blocking immunoglobulins from mice or other animals were more susceptible to this effect. When large amounts of antibody were added, the antibody excess diminished the interference. However, the presence of blocking immunoglobulins could reverse such antibody excess, actually enhancing, instead of diminishing, the positive interference. Users should be aware that blocking immunoglobulins may diminish but not necessarily eliminate this problem with such assays.
Intra-individual variation of analytes in serum from patients with chronic liver diseases.
Authors: Hölzel W G
Published: January 2020

The average biological intra-individual CV in 20 patients with chronic liver diseases (CLD), estimated for 14 analytes during a stationary phase, significantly exceeded that for a normal group in the cases of Na+, K+, Cl-, total protein, albumin, cholinesterase, hemoglobin, and alpha-amylase; it did not differ significantly from the normal group for cholesterol, alkaline phosphatase, aspartate aminotransferase, and alanine aminopeptidase; and it was significantly lower than in the normal group for alanine aminotransferase and gamma-glutamyltransferase. There were no significant sex-related differences in mean intra-individual variation in CLD patients. Individual values were gaussian-distributed for all analytes, including enzymes. The estimated biological component of intra-individual variation and the analytical variation as determined for each laboratory can be used to derive decision-making criteria in monitoring CLD.
One-tube radiotransinassay for determination of cortisol at ambient temperature.
Authors: Murphy B E , Barta A
Published: January 2020

After extraction of the sample (on filter paper) in the counting vial, cortisol is assayed by adding 50 microL of horse serum containing tritiated cortisol, and 2 mL of toluene scintillator, shaking for 20 min, and counting the radioactivity in a liquid-scintillation counter at ambient temperature. The method can be applied to saliva, serum, or urine--directly as wet samples or dried on the filter paper. Only inexpensive reagents, which are stable for months to years, are needed.
Measurement of the free alpha subunit of human glycoprotein hormones by a monoclonal antibody-based immunoradiometric assay, and further exploration of antigenic sites on the choriogonadotropin molecule.
Authors: Norman R J , Haneef R , Buck R H , Joubert S M
Published: January 2020

Three monoclonal antibodies were raised against the free alpha subunit of choriogonadotropin (hCG); each recognized a different antigenic site on the molecule. One (antibody 42) preferentially bound to the alpha subunit when it was coupled to the beta subunit as dimeric choriogonadotropin (hCG), thyrotropin (TSH), lutropin (LH), or follitropin (FSH). Antibody 71 showed some cross-reaction with intact FSH; antibody 75 was more specific for the alpha subunit. All were of low affinity (10(-7) to 10(-8) mol/L), but when combined in immunoradiometric assays (IRMAS) they proved to be as sensitive as current radioimmunoassays involving polyclonal antibodies. Advantages of the combination of antibody 75 bound to the solid phase and antibody 71 as the radiolabeled antibody were: detection limit of at least 0.1 micrograms/L; linear dilution of serum and urine; insignificant cross-reaction with intact hCG, allowing direct assay in pregnancy fluids; and a coefficient of variation less than 3% over the reference interval for nonpregnant women. There was 4% cross-reaction with intact FSH, suggesting that the epitopes recognized by nos. 71 and 75 are more exposed in FSH and that perhaps there is less folding in this molecule than in intact hCG.
Stability of free apolipoprotein A-1 concentration in serum, and its measurement in normal and hyperlipidemic subjects.
Authors: Neary R H , Gowland E
Published: January 2020

Free apolipoprotein A-1 (free A-1) is a low-molecular-mass complex of protein and lipid containing apolipoprotein A-1 (apo A-1). Using crossed immunoelectrophoresis, we separated free A-1 from the apo A-1 in high-density lipoproteins (HDL) and quantified free A-1 by comparison with a reference serum (containing 1.45 g of apo A-1 per liter) diluted in 9 mol/L urea solution. This latter treatment yields apo A-1 containing protein-lipid complexes of the same size and electrophoretic mobility as free A-1. Within-day precision (CV), determined by replicate analysis of two samples with mean free A-1 concentrations of 48 and 138 mg/L, was 9.1 and 7.2%, respectively. We also showed that the concentration of free A-1 is not stable in serum or plasma either at 4 degrees C or when frozen. The mean concentration of free A-1 in 28 fasted, healthy subjects was 75.3 (SD 13.6) mg/L. The postprandial increase was not statistically significant. The percentage of total apo A-1 in the free form in serum ranged from 3.5% to 8.1%, less than the 10% to 30% reported by others who used radial immunodiffusion to measure free A-1. Because radial immunodiffusion does not separate free A-1 from HDL, we believe that that technique overestimates free A-1. We also used crossed immunoelectrophoresis to measure free A-1 in 76 hyperlipidemic patients. Those with Fredrickson types III and V had significantly increased concentrations of free A-1 (P less than .0001). Correlations between free A-1 and cholesterol and triglycerides in serum were significant (P less than .005 and P less than .001, respectively). Possible roles for free A-1 in lipid metabolism are discussed.
A calibrated fluorescence polarization assay for assessment of fetal lung maturity.
Authors: Russell J C
Published: January 2020

The mechanism of a new fluorescence polarization method for measuring phospholipid in amniotic fluid is described. The fluorescence polarization of a surfactant fluorescent dye solubilized in amniotic fluid correlates significantly with the L/S ratio. Model studies indicate that this results primarily from partitioning of the dye between endogenous albumin, which causes a high fluorescence polarization, and dispersed phospholipid, which causes a much lower polarization. The fluorescence polarization can be compared with a calibration curve to give the ratio of phospholipid to albumin in the sample. This procedure may prove useful in antenatal assessment of fetal lung maturity.
Fluorescence polarization immunoassay evaluated for screening for amphetamine and methamphetamine in urine.
Authors: Caplan Y H , Levine B , Goldberger B
Published: January 2020

We studied the recently developed Abbott fluorescence polarization immunoassay (FPIA) for amphetamine and methamphetamine in urine and compared the results with those of the Syva enzyme-multiplied immunoassay technique (EMIT) and a gas-chromatographic assay. The FPIA method showed a limit of quantification of 0.3 mg/L, comparable with the lower cutoff of the EMIT assay. FPIA demonstrated greater specificity than the EMIT assay: phenylpropanolamine and ephedrine showed extremely limited cross reactivity with the FPIA antibody. Analysis of 249 urine specimens by all three methods clearly demonstrated the FPIA method to be acceptable for screening for amphetamine and methamphetamine in urine.
Data-reduction methods for immunoradiometric assays of thyrotropin compared.
Authors: Haven M C , Orsulak P J , Arnold L L , Crowley G
Published: January 2020

In an attempt to optimize curve fitting for immunoradiometric assays, we investigated eight data-reduction methods with two commercially available assays of thyrotropin. In four of these methods linear data-reduction models are used: logit-log programs of Iso-Data, Micromedic, and Hewlitt-Packard, and probit-log of Hewlitt-Packard. The other four were nonlinear data-reduction models: Iso-Data's "French curve" (modified spline), four-parameter logistic function, and point-to-point methods, as well as a nonlinear least squares method. In using the eight data-reduction methods on data from analyses of 78 patients' samples, we found clinically relevant differences between models. In fact, differences found by changing data-reduction models were greater than the difference between the two commercial kits.
Thin-layer chromatographic determination of urinary excretion of lactulose, simplified and applied to cystic fibrosis patients.
Authors: Flick J A , Schnaar R L , Perman J A
Published: January 2020

Urinary excretion of orally administered lactulose is used as an index of intestinal permeability. We have developed a simple thin-layer chromatographic technique for measuring lactulose in urine, using silica gel 60 plates and a propanol-borate solvent system. Lactulose concentrations as low as 62.5 mg/L can be detected with high reproducibility and without interference by urinary chromogens. After oral administration, the urinary excretion of lactulose in 8 h equaled 2.33 (SD 1.86)% in 15 patients with cystic fibrosis, as compared with 0.13 (SD 0.12)% in 16 healthy subjects (P less than 0.001).
Anomalous thyrotropin values.
Authors: Ratnaike S , Goodwin M , Deam D
Published: January 2020

We studied problems associated with use of an "ultrasensitive" thyrotropin (TSH, thyroid-stimulating hormone) assay for diagnosis of hyperthyroidism. Of 955 TSH assays performed in our laboratory during four months, 135 gave TSH values less than 0.1 milli-int. unit/L. We noted low TSH values at all concentrations of free thyroxin (FT4) in plasma. Nine of 13 patients with a normal or low FT4 and no obvious endocrine explanation for a low TSH were elderly and ill. This raises questions about the pituitary function in such patients. Twenty-seven patients who had high FT4 and non-suppressed TSH were clinically euthyroid, 20 of them being on treatment with thyroxin or amiodarone. Low TSH values in a hospital environment do not always indicate hyperthyroidism, although a normal value for TSH probably indicates euthyroidism.
Immunoenzymatic quantification of low concentrations of thyrotropin.
Authors: Lee H Y , Pekary A E , Smith V P , Sladek J , Hershman J M
Published: January 2020

We evaluated an immunoenzymatic assay (Abbott HTSH EIA) for thyrotropin (TSH) as a tool for detecting hyperthyroidism and for monitoring thyroid hormone suppressive therapy in patients with nodular goiter, thyroid carcinoma, and hypopituitarism. We also tested with thyroliberin (TRH), to determine the correlation between peak and basal TSH in suppressed patients. For comparison, we used a nonequilibrium radioimmunoassay optimized for maximum sensitivity (J Clin Endocrinol Metab 1975;41:676). Hyperthyroid patients with values for either or both triiodothyronine and thyroxin above the normal reference interval had Abbott assay values less than or equal to 0.2 milli-int. unit/L, clearly below the Abbott assay normal range, as determined in 116 euthyroid subjects. We detected one-third of the suppressed patients (greater than or equal to 0.3 milli-int. unit/L) with RIA, 69% with the Abbott assay (TSH greater than or equal to 0.04 milli-int. unit/L). Only 20% of patients with undetectable basal TSH values in the Abbott assay responded to TRH with a detectable peak TSH value; the peak TSH value after TRH was proportional to the basal TSH value. A single basal TSH measurement by the Abbott HTSH EIA should be adequate for monitoring the degree of thyroidal suppression in thyroid-hormone-treated patients.
Cyanide concentrations in blood after cigarette smoking, as determined by a sensitive fluorimetric method.
Authors: Lundquist P , Rosling H , Sörbo B , Tibbling L
Published: January 2020

Using the sensitive fluorimetric method described here, we evaluated the determination of blood cyanide as a method for monitoring exposure to tobacco smoke. The mean concentration of cyanide in blood from eight nonsmokers was 0.098 (SD 0.036) mumol/L. The concentration of cyanide in blood of smokers who had refrained from smoking for at least 2 h before sampling peaked immediately after the subjects smoked a cigarette, then rapidly declined, with a half-life of about 4 min. Its rapid disappearance from blood makes cyanide an unsuitable marker of exposure to tobacco smoke. Because the ability of patients with hepatic dysfunction to detoxify cyanide has been presumed to be impaired, we monitored the concentrations of cyanide in the blood of four patients with severe hepatic insufficiency who smoked a cigarette. The rate of elimination of cyanide from blood after smoking was only slightly less in these patients than in the controls, and the difference was not statistically significant.
New dip-and-read test for determining leukocytes in urine.
Authors: Skjold A C , Stover L R , Pendergrass J H , Corey P F , Cattell J A , Burkhardt A E , Farinelli M P , Tyhach R J , Albarella J P , Trimmer R W
Published: January 2020

A new reagent strip for the determination of leukocytes in urine (LEUKOSTIX; Ames) is described. The test is based on the esterase activity in leukocytes as a marker. Upon contact between the reagent matrix and a urine containing leukocytes, an amino acid ester is hydrolyzed by the esterase to its corresponding alcohol. The free alcohol then couples with a diazonium salt to produce a purple azo dye. The relative concentration of leukocytes in the urine is obtained by visually comparing the strip reaction with a color chart. Performance of the strip was evaluated in a clinical study involving eight different sites and 867 urine specimens. The comparison method was sediment microscopy; specimens containing five cells or more per high-power field were considered to be positive. Sensitivity was 76.3%, specificity 80.8%. Performance was comparable with that of the CHEMSTRIP LN (Boehringer-Mannheim Diagnostics, Inc.) leukocyte test, which we evaluated concurrently.
Opiates in poppy seed: effect on urinalysis results after consumption of poppy seed cake-filling.
Authors: Pettitt B C , Dyszel S M , Hood L V
Published: January 2020

We report the analysis of poppy seed filling for morphine and codeine content. Concentrations in the range 17.4 to 18.6 micrograms/g (morphine) and 2.3 to 2.5 micrograms/g (codeine) were found in different lots of the filling, which is widely used in baking. The effect of consumption of poppy seed filling on opiate urinalysis results is discussed. Morphine concentrations as high as 4.5 mg/L are reported, with persistence of concentrations greater than 0.3 mg/L as long as 35 h after consumption.
A method for simultaneously estimating plasma, erythrocyte, and leukocyte sodium, potassium, and magnesium: reference values and considerations from biological variation data.
Authors: Gallacher R E , Browning M C , Fraser C G , Wilkinson S P , MacLennan W J
Published: January 2020

We describe a method for measuring plasma, erythrocyte, and leukocyte sodium (Na+), potassium (K+), and magnesium (Mg2+) concentrations in 10-mL blood specimens. After separating cells with Ficoll-Hypaque and washing with isotonic choline chloride, erythrocytes and leukocytes are counted, so that results can be expressed as amount of substance per cell and also to monitor cell integrity and possible contamination. Plasma and cell lysates were analyzed (CV less than or equal to 7.0%) with flame photometry and atomic absorption spectrometry. Reference intervals for an elderly population with values for plasma electrolytes within reference intervals are similar to those for younger healthy subjects. From data on biological variation, reference values for erythrocyte cations are not of much use, and analytical goals for precision are not met, but the results might be useful for monitoring disease progression in individual patients. In contrast, reference values for leukocyte cations are theoretically of use and goals are achieved, but large changes are required before consecutive results can confidently be said to be significantly different.
Monoclonal antibodies used in solid-phase and liquid-phase assays, as exemplified by progesterone assay.
Authors: Schramm W , Yang T , Midgley A R
Published: January 2020

Two immunoglobulins secreted by hybridoma cell lines have been systematically investigated to determine if they could be used in solid-phase assays to give results comparable with those obtained by conventional liquid-phase radioimmunoassay (RIA). The antibodies, BQ.1 and BQ.2, bind with high specificity to the steroid hormone progesterone. The affinity constants, Ka, to 125I-labeled progesterone derivatives are 1.1 X 10(11) L/mol and 9.1 X 10(9) L/mol, respectively. Progesterone inhibited the binding of radioiodinated derivatives (amides of tyramine, histamine, and tyrosine methylester with 11 alpha-progesterone hemisuccinate) equally well. For solid-phase assays, we immobilized antibody BQ.1 via Protein A to different polystyrene surfaces (about 30 pg per tube at 50% inhibition of radiolabeled tracer). Under these conditions, the performance of this antibody for the quantification of progesterone was equivalent to that obtained in RIA. For the immobilized antibody BQ.2, only 1/10 of the amount used for optimal results in RIA was required in solid-phase assays. Binding of either antibody to the antigen was undiminished after several freezing-thawing cycles. When immobilized on solid matrices, both antibodies retained up to 95% of their binding properties for one year. Thus high-affinity, high-specificity monoclonal antibodies can be obtained for haptens and, when suitably immobilized, can be used in solid-phase assays with results equal to or better than those obtained with liquid RIA.
Development and utility of a monoclonal-antibody-based, highly sensitive immunoradiometric assay of thyrotropin.
Authors: van Heyningen V , Abbott S R , Daniel S G , Ardisson L J , Ridgway E C
Published: January 2020

Using improved selection techniques, we isolated four monoclonal antibodies with high affinity for human thyrotropin (Ka = 1.6 X 10(8) to 2.6 X 10(10) L/mol). We used two of these in an immunoradiometric assay (IRMA) that also incorporates a novel phase-separation technology (Sucrosep TSH IRMA, Boots-Celltech). This assay's very low detection limit for TSH (0.03-0.08 milli-int. unit/L) and wide working range (0-250 milli-int. unit/L) allow the differential diagnosis of hypothyroid, euthyroid, and hyperthyroid patients. We compare the utility of this IRMA with that of a RIA for patients with various thyroid disorders. As determined by IRMA, a normal concentration of TSH in serum excludes hyperthyroidism or hypothyroidism, whereas an undetectable serum TSH concentration (less than 0.08 milli-int. unit/L) accurately predicts an abnormality in thyroid gland function.
Precision of glucose measurements in control sera by isotope dilution/mass spectrometry: proposed definitive method compared with a reference method.
Authors: Pelletier O , Arratoon C
Published: January 2020

This improved isotope-dilution gas chromatographic/mass spectrometric (GC/MS) method, in which [13C]glucose is the internal standard, meets the requirements of a Definitive Method. In a first study with five reconstituted lyophilized sera, a nested analysis of variance of GC/MS values indicated considerable among-vial variation. The CV for 32 measurements per serum ranged from 0.5 to 0.9%. However, concentration and uncertainty values (mmol/L per gram of serum) assigned to one serum by the NBS Definitive Method (7.56 +/- 0.28) were practically identical to those obtained with the proposed method (7.57 +/- 0.20). In the second study, we used twice more [13C]glucose diluent to assay four serum pools and two lyophilized sera. The CV ranged from 0.26 to 0.5% for the serum pools and from 0.28 to 0.59% for the lyophilized sera. In comparison, results by the hexokinase/glucose-6-phosphate dehydrogenase reference method agreed within acceptable limits with those by the Definitive Method but tended to be slightly higher (up to 3%) for lyophilized serum samples or slightly lower (up to 2.5%) for serum pools.
Hydrocortisone succinate and hydrocortisone simultaneously determined in plasma by reversed-phase liquid chromatography, and their pharmacokinetics in asthmatic children.
Authors: Iwasaki E
Published: January 2020

Hydrocortisone succinate and hydrocortisone are chromatographed with a mobile phase consisting of sodium acetate/acetonitrile (77/23, by vol), the effluent being monitored at 254 nm. p-Hydroxybenzoate-N-propyl is used as the internal standard. Detection limits are 0.5 mg/L for hydrocortisone succinate, 0.2 mg/L for hydrocortisone. For five different concentrations the respective mean analytical recoveries were 88.2% and 100.5%, the mean intra-assay CVs for slope 3.9% and 2.1%, and the inter-assay CVs 3.3% and 1.6%. Simultaneous measurement of hydrocortisone and its succinate ester may be useful for pharmacokinetic study. Concentration-time profiles for plasma after administration of hydrocortisone sodium succinate are presented.
Technical and clinical performance of six sensitive immunoradiometric assays of thyrotropin in serum.
Authors: Rodriguez-Espinosa J , Mora-Brugues J , Ordoñez-Llanos J , Cortes-Rius M , Queralto-Companyo J M , Gonzalez-Sastre F
Published: January 2020

We evaluated the analytical and clinical performance of six commercial immunoradiometric assay kits for thyrotropin (TSH) in serum in 218 subjects, with and without thyroid dysfunction. Detection limits of the six kits were lower (from 0.07 to 0.25 milli-int. unit/L) than that of conventional TSH RIA (0.7 milli-int. unit/L). Precision was adequate over a wide range of concentrations, although interassay CVs at very low concentrations were good for only two kits (7.3% and 13.1%). Results by all the kits correlated to about the same degree with the TSH RIA (r = 0.92 to 0.98). All showed a positive correlation between both the basal and post-thyroliberin (TRH)-stimulation values for TSH (r = 0.78 to 0.88), and all showed similar euthyroid reference ranges for basal concentrations of TSH. With four of the six kits we could clearly distinguish most of the hyperthyroid patients from healthy euthyroids; however, basal and post-TRH TSH values were not sufficient to discriminate among groups of patients with different grades of thyroid hyperfunction.
Interference in an electrochemical detection system for peroxidase-linked reactions based on a fluoride ion-selective electrode.
Authors: Cowell D C , Ford P A
Published: January 2020

Use of the fluoride ion-selective electrode as a detector in a linked glucose oxidase (EC 1.1.3.4)/peroxidase (EC 1.11.1.7) method for glucose was investigated for possible interference from sugars, metabolites, drugs, and anticoagulants. The CV for the method was 1.5% (SD 0.37 mmol/L) at a glucose concentration of 25.0 mmol/L. Interference was studied with glucose at this concentration, interference being defined as any result differing by more than +/- 3 SD. When present in concentrations of clinical relevance, interference from urea, uric acid, or acetaminophen would preclude the use of this detection system for routine analysis.
Activities of dipeptidyl peptidase II and dipeptidyl peptidase IV in mice with lupus erythematosus-like syndrome and in patients with lupus erythematosus and rheumatoid arthritis.
Authors: Hagihara M , Ohhashi M , Nagatsu T
Published: January 2020

We examined the activities of peptidases in plasma and tissues of the New Zealand Black (NZB) mouse as an animal model of human systemic lupus erythematosus, and also in serum from patients with rheumatoid arthritis and systemic lupus erythematosus. Activities of dipeptidyl peptidase II (DAP II) and post-proline cleaving enzyme (PPCE) were increased, and dipeptidyl peptidase IV (DAP IV) activity was decreased in plasma and spleen of NZB mice, as compared with the control BALB/c mice. Likewise, the activity of DAP II was increased and that of DAP IV was decreased in serum of patients with rheumatoid arthritis and systemic lupus erythematosus. These results indicate the importance of hydrolytic enzymes in the pathogenesis of autoimmune diseases.
Increased activities of creatine kinase and lactate dehydrogenase isoenzymes in a patient with metastatic ovarian tumor.
Authors: Ng R H , Ethirajan S , O'Neill M , Statland B E
Published: January 2020

A 50-year-old woman with metastatic rhabdomyosarcoma of the ovary had increased activities of creatine kinase (CK; EC 2.7.3.2), CK-MB isoenzyme, lactate dehydrogenase (LD; EC 1.1.1.27), and LD-2 isoenzyme in her serum. The isoenzyme activities did not show a pattern of increasing, then decreasing. Clinical findings, including electrocardiograms, did not support the diagnosis of myocardial infarction. We suggest that high activities of CK-MB and LD-2 in serum may serve as a marker of rhabdomyosarcoma.
Performance of an automated six-wavelength photometer (Radiometer OSM3) for routine measurement of hemoglobin derivatives.
Authors: Zijlstra W G , Buursma A , Zwart A
Published: January 2020

A new instrument for spectrophotometric determination of oxygen saturation (SO2) and the fractions of carboxyhemoglobin (FHbCO) and methemoglobin (FHi), the Hemoximeter OSM3 (Radiometer), was tested by comparative measurements with a multiwavelength method. We found that it gave reliable results for freshly drawn samples from patients. When samples with artificially induced high proportions of HbCO or Hi, or both, were introduced, results were still sufficiently accurate. The presence of sulfhemoglobin (SHb) seriously interfered with the measurement of SO2, FHbCO, and FHi, but the instrument reliably indicated its presence. Because SHb is rarely encountered, a reliable warning for its presence is adequate for clinical practice. Using the instrument in its fetal mode, we obtained accurate results for blood samples from newborns.
Effects of non-ionic and anionic detergents on lipid-associated tissue ferritin.
Authors: Cham B E , Roeser P , Nikles A
Published: January 2020

Lipid-associated ferritin from homogenates of guinea pig liver is released from its conjugate(s) by incubation with the non-ionic detergents Triton X-100 and Nonidet P-40 but not by incubation with the anionic detergent deoxycholate. The amount of lipid-associated ferritin released from its conjugate(s) depends on the concentration of the non-ionic detergents. At a final non-ionic detergent concentration of about 20 g/L, all lipid-associated ferritin is released from its conjugate(s) in a liver homogenate. The amount released is identical with the amount of the lipid-associated ferritin obtained by extraction of the same liver homogenate with a mixture of butanol and diisopropyl ether.
A rapid toxicology screen for emergency and routine care of patients.
Authors: Hamlin C R
Published: January 2020

I have adapted, for use with a centrifugal analyzer, reagents from 10 different EMIT (Syva Co.) enzyme immunoassay urine drug-detection kits, reagents from another five serum kits, and reagents for determining ethanol. Assays for individual drugs in 100 microL of urine and in 100 microL of serum are performed simultaneously rather than sequentially in less than 15 min, with one-tenth the usual amount of reactants (sample + reagents). These assays, when combined with other easily performed tests, provide a rapid toxicology screen well-suited for evaluating acute emergency patients, and for performing a small number of daily routine screens. The total screen requires 500 microL of urine and 500 microL of serum. I summarize my experience with this procedure in its first year of use, and discuss differences between testing for the care of patients compared with searching for evidence of illegal drug use.
Chemical assay of p-aminohippuric acid simplified by use of dimethylaminocinnamaldehyde in ethanol.
Authors: Schwartz L B , Gewertz B L , Bissell M G
Published: January 2020

We have developed a new and simple method of p-aminohippuric acid determination by use of dimethylaminocinnamaldehyde (DACA). It differs from previous methods using DACA in that the reaction is carried out in ethanol rather than in dilute acid. This results in deeper and more stable color development. We have used this method successfully to determine effective renal plasma flow in a clinical study of this variable in pregnant women.
Value of a spectroscopic "fecalogram" in determining the etiology of steatorrhea.
Authors: Peuchant E , Salles C , Jensen R
Published: January 2020

We have developed a "fecalogram" to present the analytical results for four characteristics of fecal specimens: dry weight, total nitrogen, total fat, and hydrolyzed fat, measured by near-infrared spectroscopy. This technique gives results as precise as those of more traditional analyses for these four components. The respective correlation coefficients are 0.973, 0.960, 0.974, and 0.978. The CVs for this technique range from 1.19% to 2.88%. Among the digestive disorders revealed by this fecalogram is steatorrhea, which can be differentiated as being of pancreatic or intestinal etiology. The percentage of total fat that is hydrolyzed is significantly (P less than 0.0001) greater in patients with malabsorption (greater than 70%) than in those with maldigestion (less than 70%).
Chemically blocked analog assays for free thyronines. I. The effect of chemical blockers on T4 analog and T4 binding by albumin and by thyroxin-binding globulin.
Authors: Witherspoon L R , el Shami A S , Shuler S E , Neely H , Sonnemaker R , Gilbert S S , Alyea K
Published: January 2020

Analog assays for free thyroxin (FT4) produce inaccurate results because the T4 analog is sequestered by albumin. Diagnostic Products Corp. (DPC) introduced the concept of chemically blocking analog-albumin binding in 1982. While DPC succeeded in eliminating albumin dependence, their 1985 version of chemically blocked FT4 assay appeared to be "thyroxin-binding globulin" (TBG) dependent, producing inappropriately low FT4 results with low TBG concentrations and high results with high TBG concentrations. We examined the effects of chemical blockers on albumin and TBG binding, using equilibrium dialysis to measure free fractions of T4 analog and T4. We then created FT4 assays in which various concentrations of chemical blockers were used to demonstrate their effects on FT4 estimates in patients with low or increased TBG concentrations or who were pregnant. We found that chemical blockers do displace T4 analog from albumin, but also displace T4 from albumin and, in high concentrations, from TBG as well. It is this displacement of T4 from TBG by chemical blockers that resulted in "TBG dependence" of DPC FT4 estimates. This problem has been corrected in currently available versions of the DPC FT4 kit.
Diagnostic efficiency of four lactate dehydrogenase isoenzyme-1 ratios in serum after myocardial infarction.
Authors: Loughlin J F , Krijnen P M , Jablonsky G , Leung F Y , Henderson A R
Published: January 2020

We compared the diagnostic efficacy of the ratios LD-1/LD-2, LD-1/LD-3, LD-1/LD-4, and LD-1/LD-5 in 69 documented cases of myocardial infarction. We used 149 patients with congestive heart failure and 67 patients with nonmyocardial infarct as controls. We used a computer program to produce receiver-operating characteristic curves, decision threshold plots, and likelihood ratios for these LD ratios at 6-h intervals up to 108 h after the onset of chest pain or hospital admission. All ratios in the myocardial infarction cases peaked around 36 h after the onset of chest pain, while those for the nonmyocardial and congestive cardiac failure cases did not change over the 108-h period. In all patients with infarctions, LD-1/LD-4 and LD-1/LD-5 increased by 1.7 times (when LD-1 was less than 40%) and 3.4 times (when LD-1 was greater than 40%), respectively, over control values. Optimum decision threshold values were obtained at 13-24 h (LD-1/LD-5), 31-36 h (LD-1/LD-4 and LD-1/LD-3), and 55-60 h (LD-1/LD-2) after onset of symptoms. The highest likelihood ratio was obtained with the LD-1/LD-4 ratio; therefore, we suggest that this is a better diagnostic test for myocardial infarction than LD-1/LD-2.
Detection frequency by thin-layer chromatography of phosphatidylglycerol in amniotic fluid with clinically functional pulmonary surfactant.
Authors: Spillman T , Cotton D B , Golunski E
Published: January 2020

Densitometric lecithin/sphingomyelin ratios (LSR) and the presence of phosphatidylglycerol (PG) were determined for 735 consecutively received amniotic fluids. Of the 371 fluids with "mature" LSR between 2.0 and 4.5, more than one-third lacked detectable PG. Clinical outcomes for the 305 of the total group that were delivered within 72 h of sampling were also determined. Respiratory distress syndrome (RDS) did not occur in the 239 cases with LSR greater than or equal to 2.0, even when, as in 43 instances, PG was not detected. When the LSR was greater than or equal to 2.0, transient tachypnea was more prevalent in the absence of detectable PG (PG detected, 3% transient tachypnea; PG undetected, 16% transient tachypnea). Of the 103 cases where PG was undetected, 58% exhibited no respiratory problems. Even in the 60 cases where the LSR was less than 2.0 and PG was not detected, 42% of the cases were free of respiratory problems. RDS did not occur in any case where PG was detected, even in the six where the LSR was less than 2.0. We evaluate these results in light of various contradictory reports in the literature.
Multicenter evaluation of human placental alkaline phosphatase as a possible tumor-associated antigen in serum.
Authors: De Broe M E , Pollet D E
Published: January 2020

Using a solid-phase monoclonal antibody enzyme immuno-assay, we evaluated in a multicenter study (18 laboratories) the utility of evaluating catalytic activity of human placental alkaline phosphatase (hPLAP, EC 3.1.3.1) in serum as a potential tumor marker. We determined hPLAP in serum samples from 130 patients with ovarian cancer, 79 patients with testicular cancer (53 seminoma testis, 26 nonseminoma testis), 537 patients with various other malignant diseases (95 lung, 39 gastrointestinal, 195 breast, 208 others), 291 patients with benign diseases, and 213 healthy controls. To assess the influence of smoking on hPLAP activity in serum, we evaluated 79 serum samples from patients with noncancerous diseases for whom smoking habits had been recorded. Our main findings are: (a) hPLAP activity is frequently increased (greater than 100 mU/L) in pre-operative serum samples from ovarian cancer patients (49%) and from testicular cancer patients (59% overall; 72% seminoma, 35% nonseminoma); (b) heavy smoking may increase hPLAP activity; (c) excluding heavy smokers, a 96% specificity for cancerous lesions was observed; (d) in patients with ovarian malignancies, CA 125 and hPLAP may behave as independent markers; and (e) in patients with seminoma, hPLAP is clearly more frequently increased than is beta-choriogonadotropin.
Improved measurement of free alpha subunit of glycoprotein hormones by assay with use of a monoclonal antibody.
Authors: Whitcomb R W , Sangha J S , Schneyer A L , Crowley W F
Published: January 2020

Any exploration of the physiology of secretion of free alpha subunit of glycoprotein hormones in humans requires a sensitive assay system that shows low cross reactivity with the intact hormones (lutropin, follitropin, thyrotropin, and choriogonadotropin). We established and validated such an assay system with a monoclonal antibody for detection of free alpha subunit in serum with better sensitivity (detection limit, 30 ng/L) and less cross reactivity (0.67% with intact human lutropin) than with available polyclonal antibody methods. Thus, the specific epitope recognized by this antibody apparently is exposed only on the free or uncombined form of alpha subunit and is concealed after non-covalent combination with any beta subunit. Using Western blot analysis, we show that most of the cross reactivity is probably the result of contamination of the human lutropin standard (obtained from the National Hormone and Pituitary Program, NIH) with small amounts of free alpha subunit. With such a specific and sensitive method, it should be possible to obtain more-precise information regarding the secretion of free alpha subunit.
A laboratory and clinical evaluation of an immunochemiluminometric assay of thyrotropin in serum.
Authors: Berry D J , Clark P M , Price C P
Published: January 2020

We evaluated an immunochemiluminometric assay for human thyrotropin. A chemiluminescent acridinium ester is used as a label, with magnetic-particle separation. The lower limit of detection of the assay (mean + 3 SD of the zero standard) was 0.07 milli-int. unit/L, with a working range of 0.5 to greater than 60.0 milli-int. units/L. Assay accuracy was good as judged from analytical recovery, analysis of external quality-assessment samples, and comparison with an enzyme-amplified immunoassay. There were no significant interferences or cross-reactivities. Twenty-four samples assayed showed aggregation of the magnetic particles. On re-assay, four of these samples showed a significant increase in the measured TSH by the luminescence assay. Assay time for 60 tubes was approximately 3.5 h with the use of a semi-automated luminometer. The reference interval, determined from data on 144 healthy euthyroid subjects, was 0.3-4.0 milli-int. units/L. Sixteen of 19 thyrotoxic patients showed clearly suppressed concentrations of thyrotropin in serum.
Age-related reference values for free amino acids in first morning urine specimens.
Authors: Parvy P R , Bardet J I , Rabier D M , Kamoun P P
Published: January 2020

We determined age-related reference values for urinary free amino acids (in mmol/mol creatinine) in first morning urine specimens from 360 control subjects who were divided into nine age groups: birth to 1 month, 1-6 months, 6-12 months, 1-2 years, 2-4 years, 4-7 years, 7-10 years, 10-13 years, and older than 13 years. Except for taurine and 3-methylhistidine, the concentration of all the amino acids decreased with increasing age. The use of these results to detect aminoacidopathies and tubulopathies is discussed.
Comparison of the compression strength of human vertebral bodies with the mass and density of apatite: a study by 31P NMR spectroscopy.
Authors: Brown C E , Srinivasan R , Sigmann P , Myklebust J B , Battocletti J H
Published: January 2020

The force needed to fracture individual human thoracic and lumbar vertebral bodies is compared with the mass and density of apatite. 31P NMR spectrometry was used to quantify the apatite, because it permits the mineral content of bone to be determined noninvasively with minimal nonspecific interference from the organic matrix or from variations in composition of the marrow. Experiments were performed with bones of similar structure and function from a single individual with no history of trabecular fractures, to compensate for the effects of the other variables that affect bone strength. The coefficient of correlation between compression strength and the volume density (i.e., g/cm3) of apatite was 0.95. The correlation of strength with the mass (i.e., grams) of apatite in a vertebral body also was reasonably good, r = 0.82, but correlations with areal density (i.e., g/cm2) and linear density (i.e., g/cm) were much poorer.
Demonstration of monoclonal IgE by isoelectric focusing: first reported case of IgE myeloma in Australia.
Authors: McLachlan R , Grigg A P , Cornell F N , Harris R A , Woodruff R K
Published: January 2020

A 56-year-old man who presented with back pain was diagnosed with multiple myeloma. Serum protein analysis by isoelectric focusing identified a monoclonal IgE lambda of unique spectrotype compared with other monoclonal immunoglobulins. The similarity of the spectrotype of this monoclonal IgE to that of two purified monoclonal IgEs suggests that these proteins have a characteristic spectrotype, sufficiently different from those of other immunoglobulin classes to allow its recognition.
Strategy to diagnose monoclonal gammopathies in serum: high-resolution electrophoresis, immunofixation, and kappa/lambda quantification.
Authors: Keren D F , Warren J S , Lowe J B
Published: January 2020

Identification of monoclonal gammopathies in serum has involved electrophoresis of serum proteins, immunoelectrophoresis (IEP), and quantification of IgG, IgA, and IgM. Recent innovations in technology--including high-resolution electrophoresis (HRE), immunofixation (IFX), and quantification of kappa- and lambda-containing immunoglobulins--allow for more rapid and precise assessment of serum for monoclonal proteins. We present a series of guidelines to determine when high-resolution electrophoresis and quantification of immunoglobulins (including kappa and lambda) are sufficient and when additional IFX is required to characterize the monoclonal gammopathy. Of the samples studied, 88% were correctly diagnosed by HRE with quantification of immunoglobulins and kappa/lambda; only 12% required that IFX be performed. The guidelines allow us to detect monoclonal gammopathies quicker and more efficiently by avoiding redundant IEP or IFX testing. For the vast majority of cases, these guidelines allow for a correct diagnosis within one day. After one year of follow-up since completion of the study, no undetected cases of monoclonal gammopathy have eventuated.